50640309 a to Z of the Brain Web Version

The A to Z of The Brain

Dr A. L. Neill Neill BSc MSc MBBS PhD FACBS

TABLE OF CONTENTS

INTRODUCTION This is the 6th in the series of the A to Zs. It continues on where the A to Z of the Head & Neck left off and continues with some of the new features of the evolving series srcinal. It is the first book of an “organ” in that the Brain and CNs is a whole with multiple parts. Clinical considerations are maintained.As usual feedback plays an extremely important role in this, please feel free to comment and contribute to any and all aspects of these publications after all they are for you – whoever you, the reader may be. We have a website where you can view all images of the A to Zs and other material and from which you make comments: http://www.aspenpharma.com.au/atlas/student.htm

ACKNOWLEDGEMENT Thank you ASPENpharmacare Australia for your support andassistance in this valuable project, particularly Mr. Greg Lan CEO of Aspenpharmacare Australia, Rob Koster, Richard Clements and Ante Mihaljevic and everyone who provided valuable feedback.

DEDICATION To those striving to understand.

HOW TO USE THIS BOOK The structure of the A to Z books has by necessity changed slightly. The principle of listing all the structures in an alphabetical manner and hence making the book its own index for easy retrieval has been maintained, but because of the complexity of this material, it has been necessary to do this after first dividing the material into a number of main topics as was the case in the A to Z of the Head & Neck . Thank you Amanda Neill BSc MSc MBBS PhD FACBS SBN 978-0-9806840-2-5

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Table of contents Introduction Acknowledgement Dedication How to use this book Table of contents Abbreviations Common Terms used in Neurology – Neuroanatomy Guide to Anatomical Planes and Relations Anatomical movements The Nervous system – overview The Nerve Cells – overview The Brain and SC – overview Blood brain barrier Blood supply CSF

3 3 3 3 4 9 10 24 26 28 30 32 32 34 38

Development and Organization Macroscopic structure Fibrous tracts Meninges – coverings Dura Mater Meninges and the Brain Meninges and the SC Neurological assessment – Headache History Examination - conscious patient unconscious patient

40 42 44 46 46 48 50 52 52 52 56 57

THE BRAIN Blood supply – overview Blood Vessels and Meningeal layers of the Brain Brain Arteries - overview see also Cerebrum / arteries Brain Veins - overview Cranial Venous Sinuses Cavernous sinus Petrosal sinuses see Sagittal sinuses Sagittal sinuses Straight sinus see Veins overview & Sagittal sinuses Transverse sinus see Veins overview & Sagittal sinuses Brodmann’s areas see Cerebrum Circle of Willis = Cerebral arterial circle 4

60 64 66 68 68 70

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Topography Macroscopic components of the Brain Outer surfaces – see also Gyri & Sulci Inferior Lateral Posterior Sagittal - Median = mid-sagittal Superior see Cerebrum Gyri + Sulci / Outer surfaces Dissections – Sectional Anatomy Coronal sections Sagittal sections see also Median section Transverse sections see also Coronal sections

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78 84 90 92

REGIONS Amygdala / Amygdaloid bodies see Fornix Angula gyrus see Cerebrum/lobes Anterior Commissure 94 Anterior Perforating substance see Brain outer surfaces / inferior Basal ganglion/nuclei see also Brainstem and Diencephalon 96 Basis Pedunculi = Crus cerebri see Brainstem Midbrain Brainstem = Midbrain + Pons + Medulla Oblongata 98 Arteries 102 CN nuclei see also Cranial Ns Broca’s area see Language centres Bulb = Medulla Oblongata see Brainstem , Midbrain Cerebrum Arteries Brodmann’s areas and maps of the cerebral cortex Examination of CH - cognitive skills Lobes – Cerebrum Major anatomy Sections – coronal / transverse see Dissections/Coronal, Transverse Caudate nucleus see Basal nuclei Cerebellum Choroid plexus see Basal Nuclei, CSF, Ventricles Cingulate see Cerebrum/lobes see Anterior commissure Claustrumgyrus Colliculi - superior & inferior bodies see Brainstem Corpus Callosum see also the Brain Dissections Sagittal Corpus striatum = Caudate nucleus + Lentiform nucleus – see Macroscopic structure, Basal Nuclei 5

104 106 113 114

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Crus Cerebri see Brainstem Midbrain Cuneus see Lobes - Occipital, Brain sagittal Dentate nuclei see Brainstem, Cerebellum, Limbic system Dermatomes (of the Face) – see Cranial Ns and Special senses / CN V Trigeminal N Diencephalon = Epithalamus + Hypothalamus + Thalamus 126 Dura Mater see Meninges coverings Ependyma see Ventricles External Capsule see Brain/sections/coronal Falx Cerebri see Meninges –brain coverings Fornix see also Septum Pellucidum 128 Frontal lobe see Brain - Outer surfaces / Cerebrum Lobes Geniculate bodies – lateral / medial see Brainstem, Midbrain Globus Pallidus see Anterior Commissure Habenular nucleus see Basal nuclei, Hypothalamus Hippocampus see Fornix, Limbic system Hindbrain see Brainstem, Midbrain Hypothalamus see Basal nuclei, Diencephalon Inferior Colliculus see Brainstem Infundibulum see Brain/outer surfaces/inferior Insula see Cerebrum/lobes Internal Capsule see Brain/sections/coronal Language centres see also Pathology / Aphasia 130 Lateral Sulcus = Sylvian fissure see Cerebrum/lobes, Gyri + Sulci Lentiform Nucleus = Globus Pallidus + Putamen see Basal nuclei, Hypothalamus Limbic system see also Fornix 132 Mammillary bodies (AKA Mammilary) see Fornix, Limbic system Medulla Oblongata = Medulla see Brainstem , Midbrain Midbrain = Mesencephalon see also Brainstem 134 Nucleus Accumbens = septal nuclei see Basal Nuclei, Fornix Obex see Ventricles Operculum see Cerebrum /lobes Optic radiation see CN II Paraterminal gyrus = Subcallosal gyrus see Anterior commissure, Septum Pellucidum Pineal body/gland see Brain- Outer surfaces - Median Pons see Brainstem, Midbrain Precuneus see Cerebrum/lobes, Brain sagittal Pulvinar (part of the Thalamus) see Thalamus 6

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Putamen see Basal Nuclei Red Nucleus see Brainstem, Midbrain, Rubrospinal tract Rhinencephalon = the Olfactory region of the brain – see Septum Pellucidum, CN I Septum Pellucidum Striate body = Corpus Striatum Substantia Nigra see Brainstem Superior Colliculus see Brainstem Sylvian fissure = Lateral Sulcus see Cerebrum Tela Choroidea see, Hypothalamus, Ventricles Thalamus see also Basal ganglia & Diencephalon Uncinate Fasciculus see Anterior Commissure Vallecula see Cerebellum Ventricles Vermis see Cerebellum Wernicke’s area see Language centres

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THE CRANIAL NERVES & SPECIAL SENSES Overview and summary 148 BS to the CNs and Relations see also the Brain veins CN I see also Special senses / Smell & Taste 152 Medications affecting Smell & Taste Pathology of Smell & Taste CN II see Brain outer surfaces /inferior; Special senses / Sight CN III see also Special senses / Sight 153 CN IV see also Special senses / Sight 156 CNV 158 CN VI see also Special senses / Sight 172 CN VII see also Brainstem CN nuclei / Special senses / Taste 174 CN VIII see Special senses / Sound and Balance 182 CN IX see also Special senses / Taste 186 CN X see also Special senses / Taste 188 CN X special anatomy – Larynx 192 CN X + ANS 194 CN XI see also CN IX X & XI 200 CN IX, X & XI neural pathways & interrelationships CN XII

SPECIAL SENSES Sight = Vision + Focus and eye movement Vision- CN II Visual field defects 7

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Control of eye movement and focus - CN III, IV & VI see also Venous sinuses/Cavernous sinus Smell & Taste Smell - CN I see Rhinencephalon Taste – CN VII, IX & X Sound + Balance CN VIII

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Examination of the CNs Reflexes of the CNs -

230 238

THE SPINAL CORD Ascending = Sensory tracts Anterolateral system = Spinothalamic + Spinoreticular tracts (pain &temperature)see Pain pathways Dorsal columns = Fasciculi Cuneatus + Gracilis (touch, proprioception & vibration) Spinocerebellar tracts = anterior + posterior spinocerebellar tracts see Dorsal Columns Spinothalamic tracts = anterior + lateral spinothalamic tracts see also Pain pathways Descending = Motor tracts Anterior corticospinal tracts = uncrossed pyramidal tracts see Corticospinal tracts Corticobulbar = Rubrospinal see Pyramidal tracts Corticospinal = anterior + lateral corticospinal Extrapyramidal tracts = Tectospinal + Vestibulospinal + Spinocerebellar tracts see Tracts of the SC Lateral corticospinal tracts = crossed pyramidal tracts

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252 254

see Pyramidal tracts Pyramidal = corticobulbar tracts + corticospinal tracts 256 Rubrospinal = Corticobulbar see Pyramidal tracts Nociceptive information see Pain pathways Pain pathways 258 Overview of tracts of the SC 260 Points of immobility 262 Relations with the ANS 264 Sensory modalities eg pressure, proprioception, temperature, touch, vibration see Tracts of the SC for description of individual modalities Structure overview see The Brain and SC - overview Tracts of the SC Examination of the SC, Spinal N roots and PNs see the A to Z of the Bones, Joints & Ligaments and the Back & The A to Z of the Peripheral Nerves Overview of CNS disease 8

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Abbreviations A

= actions /movements of a joint A = anterior ACF = anterior cranial fossa aka = also known as alt. = alternative

L L LL Lt. lig M MB MC

= = = = = = = =

lateral left / lumbar lower limb Latin ligament mater midbrain metacarpal

AM = arachnoid mater ANS = autonomic nervous system ant = anterior art = articulation (joint w/o the additional support structures) AS = Alternative Spelling, generally referring to the diff. b/n British & American spelling assoc. = associated with BBB = blood brain barrier bc = because BP = brachial plexus BS = blood supply BS = brain stem b/n = between C = cervical / carpal CC = cerebral cortex c.f. = compared to CF = cranial fossa(e) CH = cerebral hemispheres CN = cranial nerve CNS = central nervous system CO = cardiac output Co = coccygeal CoP = coccygeal plexus collat. = collateral Cr = cranial CSF = Cerebrospinal fluid CT = connective tissue DH = dorsal horn (of thespinalcord) dist. = dis tal DM = dura mater e.g. = example

MCF = middle cranial fossa med = medial MO = medulla oblongata (medulla) MN = myelinated nerve nMN = non-myelinated nerve N = nerve NS = nervous system/nerve supply NT = nervous tissue NTr = nerve tract / trunk P = posterior

EC Gk. GM Hp IC IC IMC jt(s)

VC VH cord) Ven WM w/n w/o

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= = = = = = = =

extracellular (outside the cell) Greek grey matter Hippocampus intracellular / intercostal intercarpal intermetacarpal joints = articulations

PaNS = parasympathetic nervous system PCF = posterior cranial fossa pl. = plural PM = pia mater PN = peripheral nerve post. = posterior proc. = process prox. = proximal R = Right RC = radiocarpal S = sacral sing. = singular Sc = spinal canal SC = spinal cord SN = spinal nerve SP = spinous process SyNS = sympathetic nervous system T = thoracic TP = transverse process UL = upper limb, arm V = vertebra VB = vertebral body = vertebral column = ventral horn (of the spinal = = = =

ventricle (of the brain) white matter within without © A. L. Neill

INTRODUCTION

Neuro-anatomical and Neurological terms Action potential Acusis Adiadochokinesia Afferent

the generation of a N impulse through stimulation and depolarizing of the N cell membrane hearing inability to rapidly perform rapidly alternating movements incoming - as with sensory fibres see Sensory

Agnosia

w/o knowledge inability to recognize sensory stimuli (auditory, tactile, visual) Agraphia w/o writing - inability to write coherently – due to a cerebral lesion Ala cinerea ashen hued wing - triangular region on the floor of the 4th Ven – one of the Vagal nuclei Alexia w/o words - inability to grasp the meaning of words Allocortex the older cerebral cortex = archicortex + paleocortex Alveus trough – thin WM layer covering the ventricular surface of the Hp Amacrine

long - the N cell type with long fibrous processes in

the retina Ammon’s horn Ammonis = Egyption god with a ram’s head used for the Hp which sagittally has a curl like a ram’s horn Amygdala almond - almond sha ped body in the Temporal lobe involved in memory & emotion Anasthesia w/o feeling - loss of sensation Angular gyrus part of the Temporal lobe involved in language processing, letter shape and word recognition, connects occipital cortex with Wernicke’s area Anopsia w/o sight - defect of vision Ansa loop - a loop like structure eg Ansa Cervicalis Ant. Cingulate gyrus part of the limbic system - assoc. with cognitive processing of pain perception and emotional response (see cingulum) Antidromic N impulse running up the axon or down the dendrite in the opposite direction Aperture an opening or space b/n bones or w/n a bone. Aphasia w/o speech - loss of speech or comprehension of the written and spoken word Apraxia

w/o being able to do - inability to move purposefully w/o paralysis Arachnoid spidery – weblike eg AM Archeocortex AS Archiocortex part of the 3 layered Allocortex in the Limbic system – mainly in the Hp and Dentate gyrus Archicerebellum AS Archeocerebellum old part of the little brain – to do with balance 10

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caudal area on the floor of the 4th Ven joint, which is a point of contact b/n 2 bones / relating to a joint. - hence articular branches of a N supply the joint described. Association fibres those N fibres which connect cortical areas of the brain ipsilaterally (as opposed to commissural fibres) Astereognosis w/o solid shape - inability to recognise basic shapes Area postrema Articulation

by feeling them star - one of the supportive cell types in the CNS (see Glia) w/o work - disturbance in the muscle contraction sequence in doing a coordinated act Ataxia w/o order inability to contract muscles in order and hence weakness in contraction Athetosis w/o position inability to keep fingers or toes in a still position continually writhing of the extremities – due to degeneration in the CC and Corpus Striatum Autonomic automatic motor innervation of the viscera Axial axis - refers to the head and trunk (vertebrae, ribs and sternum) of the body. Axolemma plasma membrane of the axon Axon N process carrying material away from the cell body to the target organ, each N has only one axon Axon collaterals branches of the axon Axon hillock part of the N where the axon rises and has no Nissl bodies Axoplasm cytoplasm of the axon Baroreceptor weight receiver sensory N fibre which responds to Astrocytes Asynergy

pressure changes as in the carotid canal incorrect term for cluster of Ns buried in the WM of the brain and involved in movement includes: CAUDATE NUCLEUS + PUTAMEN + GLOBUS PALLIDUS + SUBSTANTIA NIGRA Basilar relating to the base or bottom of structures Basiocranium bones of the base of the skull Basis pedunculi (see crus cerebri) Bipolar neurons with 1 dendrite + 1 axon (see unipolar, multipolar) Blood brain barrier = BBB the barrier protecting the brain from certain substances found in the BS Brachium arm - large bundle of N fibres joining one region to another Bradykinesia abnormally slow movements Brainstem MO + Pons + Midbrain Broca’s area central region of the L frontal lobe of the CC - involved in the production of speech: - word perception, Basal ganglia

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production, sound and memory Brodmann’s areas areas of the CC which have been designated by their histology – cytoarchetecture - and later analysed and found to have specific functions (after Korbinian Brodmann 1909) Bulb old term for MO / in the corticobulbar tract refers to the that part of the brain stem containing the motor nuclei of the CNs Calamus Scriptorius reed / pen - caudal part on the floor of the 4th Ven which looks like a pen Calcar spur as in the Calacarine sulcus of the Occipital lobe Canal tunnel / extended foramen as in the carotid canal, at the base of the skull adj canular (canicular - small canal) Caput relating to the skull Carotid to put to sleep; compression of the common or internal carotid artery causes coma. This refers to bony points related to the carotid vessels CAT scan =

computerized axial tomography scan – computer mediated Xray image depicting a crossection of the body see also CT scan Cauda equina horse’s tail - lumbar and sacral N roots of the SC resembling a horse’s tail Caudate nucleus tail nucleus in the Corpus Striatum, having a long tail Cavity an open area hence an open area or sinus w/in a bone or formed by 2 or more bones (adj. cavernous), may be used interchangeably with fossa. Cavity tends to be more enclosed fossa a shallower bowl like space (Orbital fossa-Orbital cavity). Central sulcus major groove in the coronal plane dividing the frontal and parietal lobes Cephalic pertaining to the head Cerebellum little brain – the brain situtated in the PCF - to do with motor coordination, balance and posture – same structure as the Cerebrum – 2 hemispheres cortex and medulla - only smaller Cerebrospinal fluid = CSF fluid - fluid surrounding the brain and SC formed by the ependymal cells from filtered blood. It is part of the BBB, and contains sugar, urea and protein - approx 125mls and flows around the brain and SC at any time. Cerebral cortex GM interconnection b/n the 2 sides via the Corpus Callosum Cerebral hemispheres = CH L mainly to do with: speech, writing, language & calculation R mainly to do with spatial abilites, face 12

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recognition, music perception and production - see Cerebrum Cerebro-spinal fluid = CSF , fluid surrounding the Brain + SC providing insulation, nutrition and pressure Cerebrum Brain – the major 2 hemispheres of the brain – consisting of an outer cortex of Ns = GREY MATTER GM) + inner medulla of N fibres WHITE MATTER (WM) Chiasma Chorea

(Gk = ) used for the crossing of the Optic fibres dance – irregular, involuntary, movements of the limbs and face – due to degen. of the neostriatum Choroid AS Chorioid delicate membrane – as in the choroid plexus in the brain or the retina Cinerea ashes / ashen colour / grey – as in Tuber Cinereum ventral portion of the Hypothalamus Cingulate gyrus part of the Limbic System, directly above the corpus callosum on the medical surface of the CH –to do with emotion and attention Cingulum

girdle as in a bundle of association fibres in the WM of the Cingulate gyrus of the CH, medial surface Claustrum barrier - thin sheet of GM b/n Lentiform nucleus and the Insula Cochlea a snail hence snail-like shape relating to the Organ of Corti in the middle ear (adj. cochlear) Cognition to know – a processing of knowledge for use in higher functions as in recognition and recall for use in problem solving etc Colliculus small elelvation / mound – e.g. superior and inf. colliculi forming the tectum of the MB – Facial colliculus on the floor of the 4 th Ven Commissural fibres those N fibres crossing the Median plane in the brain or SC (e.g. anterior commisure) Commissure joining together - a decussation or crossing of large groups of fibres from one side of the median plane to the other in the brain or SC Cordotomy AS Chordotomy –sectioning of spinothalamic tract for intractable pain (also tractotomy) Contra opposite (as opposed to ipsi – the same) Contralateral on the opposite side (as opposed to ipslateral on the same side) Corona crown – fibres radiating from an inner point outwards - as in the Corona Radiata – fibres from the internal capsule to the CC Corpus Callosum hard body – the main neocortical commissure of the 13

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CH – connects the 2 CH via large mass of axons crossing from one side to the other Corpus Striatum striped body - mass of GM with motor functions at the base of each CH Cortex outer rind / bark – outer GM of the cerebrum and cerebellum Cortical plasticity ability of connections b/n Ns of the CC to change Cranial Nerve (CN) N coming directly from the brain not the SC Cranium the cranium of the skull comprises all of the bones of the skull except for the mandible. Crest prominent sharp thin ridge of bone formed by the attachment of muscles particularly powerful ones e.g. Temporalis/Sagittal crest Crus leg – e.g. Crus Cerebri - the ventral part of the Cerebral Peduncle of the MB CT scan = computerized axial tomography scan – computer mediated Xray image depicting a cross-section of the body see also CAT scan Cuneus wedge – e.g. gyrus on the medial surface of the CH – Fasciculus Cuneatus of the MB & SC Cutus skin - hence cutaneous branches refer to the Ns supplying the skin & adnexae Declarative memory memory of words which can be recalled Decussation X - a crossing of paired N fibres inside the CNS e.g. in the pyramids, medial leminisici and superior cerebellar peduncles Dendrite(s) tree - N process(es) bringing communication to the cell body Dentate toothed – e.g. Dentate nucleus in cerebellum – Dentate gyrus in the Temporal lobe Depolarization the loss of the potential across the cell membrane of a N due to stimulation and formation of a N impulse (see repolarization) Dermatome the cutaneous innervation of a SN Diencephalon through the brain = Epithalamus + Thalamus + Subthalamus + Hypothalamus Diplopia Distal Dura Dyskinesis

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double vision further away from the axial skeleton (opposite of Proximal) hard – as in DM – thick external layer of the meninges disordered movement – abnormal motor function with involuntary purposeless movements © A. L. Neill

INTRODUCTION

Dysmetria

disordered measure – abnormal reach or control of muscle action Efferent outgoing as in Motor nerves - see Motor Emboliform plug – e.g. emboliform nucleus of the cerebellum Endocranium w/in the skull - refers to the interior of the “braincase” adj. endocranial divided into the 3 major fossae anterior (for the Frontal lobes) middle (containing Temporal lobes) and posterior (for the containment of the Cerebellum). Endoneurium

w/in the N - innermost of the CT coverings of a PN fibre (see neurium, perineurium and epineurium) Engram mark – a lasting memory – memory picture from a past experience Entorhinal w/in the nose – the entorhinal area lies in the ant. of the parahippocampal gyrus – in the lateral olfactory area Ependyma/ Ependymal cells line the ventricles and the central canal of the SC (see Glia) form the CSF Epineurium upon the N - outermost of the CT coverings of a PN fibre (see neurium, perineurium and endoeurium) Epithalamus upon the inner chamber – region of the diencephalons above the thalamus includes the pineal body Extradural space space external to the Dura mater but w/n the skull or boney canal of the SC Extrapyramidal system all the motor parts of the CNS except the pyramidal system Extrastriate visual areas of the CC assoc with higher order visual recognition eg face recognition Falx sickle as in falx cerebri, falx cerebelli Fascis bundle Fasciculus small bundle – used for a bundle of N fibres Fastigial gabled roof top – eg the Fastigial nucleus at the top of the cerebellum Fimbria fringe – band of N fibres along the edge of Hp continues as the fornix Forceps paired tongs – as in the U shaped fibres of the Corpus Foramen Fornix

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Callosum - Forceps frontalis and Forceps occipitalis a natural hole in a bone usually for the transmission of BVs &/or nerves.(pl. foramina). an arch – as in the efferent N tract of the Hp which arches over the Thalamus and teminates in the Mammillary body © A. L. Neill

INTRODUCTION

Fovea Funiculus

Funis Ganglion

pit – as in the Fovea Centralis at the centre of the retina little cord – as in the cords of WM in the SC which consist of a number of different fasiculi all running together in the Lateral Funiculus of the SC cord knot - collection of N cell bodies outside the SC (also incorrectly used for isolated islands of N cells w/n in

the WM of the brain eg Basal Ganglia of the brain - see Basal Ganglion) , pl ganglia an abnormal collection of neural tissue found subcutaneously Gemmule small bud – swellings on the ends of some dendrites in the CNS Genu knee – anterior end of the Corpus Callosum = the genu of the Corpus Callosum; geniculate ganglion of the Facial N; geniculate nuclei of the Thalamus Glia / Glial cells glue associated supporting cells of the CNS connective tissue and immune functions, types: astrocytes, oligodendrocytes, ependymal cells and microglia pale ball – medial part of the Lentiform nucleus of the Corpus Striatum - part of the basal ganglia Glomerulus small knot, tangle – synaptic glomeruli of the olfactory bulb Grey Matter (AS Gray) N tissue in the brain and SC which contains mainly N cells, dendrites unmyleinated axons & glial cells (opposite to WM which contains mainly myelinated axons) Gracilis slender – Fasiculus Gracilis of the SC; Nucleus Gracilis Globus pallidus

of the of the Medulla long pit or furrow a circle, hence a coil of brain cortex generally the CC. half stroke – paralysis down one side of the body sea horse – a neural gyrus in the Limbic system (in the Temporal lobe) producing an elevation on the floor of the temporal horn of the lateral Ven. - involved in the conversion of short term memory to long term memory Homunculus little human - any representation of a human being, in this context - the homunculus maps of the motor and somatosensory cortex show how many neurons are devoted to various regions of the body Horn projection of GM in the SC (ant. & post. horns are for motor & sensory Ns respectively) Hydrocephalus water in the head – swelling in the cranium due to CSF accumulation Groove Gyrus Hemiplegia Hippocampus

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Hypothalamus

under the inner chamber – region in the Diencephalon which controls the ANS and the Pituitary gland Impulse a depolarization of the N membrane resulting in the promulgation of a signal along the N process. Inferotemporal cortex lower part of the Temporal lobe involved in number and object recognition Infundibulum funnel / stem – stalk of the ant. pituitary = Insula Inter Interneurons Intra Introitus IpsiIpsilateral Isocortex Kinesthesia Lacerum

Lacrimal Lateral sulcus

neurohypophysis island – CC concealed from the surface at the bottom of the Lateral Sulcus = Island of Reil between act b/n motor and sensory Ns in a reflex - transferring the signal from the sensory to the motor w/o higher imput within an orifice or point of entry to a cavity or space. same – as opposed to contra- opposite on the same side as opposed to contralateral equal bark – the CC which has 6 layers = neocortex movement sensation – the perception of moving and movement something lacerated, mangled or torn - eg Foramen Lacerum, small sharp hole at the base of the skull often ripping tissue in trauma. related to tears and tear drops. (noun lacrima) groove running across the cerebrum in the coronal plane separating the frontal & parietal lobes

Lambda

from the Greek letter a capital 'L' and written as an inverted V.(adj. lambdoid) and used to name the point of connection between the 3 skull bones Occipital and Temporals. Lamina a plate - the lamina of the vertebra is a plate of bone connecting the vertical and transverse spines (pl. laminae) Leminiscus ribbon -ribbonlike, flat band of N fibres in the CNS e.g. Lateral & Medial Leminisci Lentiform lenslike – Lentiform nucleus of the Corpus Striatum Limbic System group of brain structures to regulate emotion Limbus

Linea 17

and memory border – as in the Limbic System which has a border of CC on the medical surface of the CH consisting of: septal areas, cingulate and parahippocampl gyri, mammillary bodies and ant. thalamic nuclei a line - as in the Nuchal lines of the Occitipum © A. L. Neill

INTRODUCTION

Locus a place -c.f. location, locate, dislocate. Longitudinal sulcus deep sulcus or groove along the mid-sagittal plane of the brain separating the R & L CH Macula spot – as in the Macula Lutea of the retina = yellow spot Magnetic Resonance Imaging = MRI used to “see” soft tissues other forms are fMRI which allows for images of soft tissues as they change see MRI Magnum Mammillary AS Mamillary Medulla Meninges

large pl magna little nipple – mammillary body in the ventral surface of the Thalamus marrow middle – Medulla Oblongata – the caudal portion of the brain stem , spinal medulla coverings of the brain and SC made up of 3 layers Dura (hard) mater on the outer to protect the NT; Arachnoid (spidery) mater in the middle to support the BS and Pia (soft) mater, the inner coating to coat the

NT and act as a barrier to foreign substances. CSF flows b/n the inner 2 coverings. Macroglia large supportive cells of the CNS (see Glia) Microglia phagocytic cells of the CNS (see Glia) Miosis excessive contraction of the pupil due to drugs or disease Mixed N a N containing both sensory & motor components, most peripheral Ns are mixed Mnemonic memory Motor / motor N causes muscle contraction. these Ns are efferent or moving away from the SC Motor cortex part of the brain – cerebral motor cortex - responsible for executing bodily movements Motor program a sequence of muscle contractions needed for a complex movement MRI technique to see images of soft tissues eg. the brain using magnets Multipolar referring to a N which has many dendrites + 1 axon (see unipolar, bipolar) Myelin marrow - the phospholipids produced by Schwann

Myotome “Nerve” (N)

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cells to insulate the axons of PNs and allow impulses to travel for longer and faster to the target organ the muscular innervation of a SN N cell (neuron) capable of transmitting or firing off a signal caused by ion transfer - excitable cell N process - generally Axon carrying the impulse to the skeletal © A. L. Neill

INTRODUCTION

Neurilemma processes Neurium

muscle site general term meaning either the neuron(s), process(es) or part of a bundle of neurons, either cranial, spinal or peripheral layers of Schwan cell membranes coating axon general term for the CT covering of a PN fibre (see endoneurium, perineurium and epineurium)

Neurocranium Neuroglia Neuron Neurotransmitter

refers only to the braincase of the skull. see Glia Nerve cell substances in vacuoles at the foot of the nerve process which are released to induce a N impulses or in response to a N impulse Nociceptive injury – nociceptors respond to injurious stimuli Nucha The nape or back of the neck adj.- nuchal Nystagmus sleepy – involuntary oscillations of the eyes Occiput The prominent convexity of the back of the head Occipitum = Occipital bone adj. occipital Oligodendrocytes in the CNS only, become Schwann cells in the PNS and SC, act as a barrier and insulator of axons and neurons Osmatic to do with the sense of smell Pars a part of Pathway general term indicating a path of defined N fibres Perineurium middle of the 3 CT coverings of a PN fibre (see neurium, perineurium and epineurium) Peripheral N (PN) coming from the SC, - often the combination of 1 or more SNs or part thereof and not the brain directly (cranial N) see Spinal N Peroneal pertaining to the lower leg Pi a soft – pia mater PM soft covering of the brain Pineal pine cone shaped – pineal body = pineal gland Plexus plait / knot – an interlaced network of Ns – brachial plexus Polarization the maintenance of an unequal charge across the membrane of the N, allowing the cell to be stimulated - all excitable cells have a polarized membrane Pons bridge – part of the brainstem which lies b/n the medull and the midbrain Posterior part of the CC which transforms visual information Parietal cortex into motor commands Precentral gyrus site of the primary motor cortex Prefrontal cortex involved in complex decision making, behavioural 19

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INTRODUCTION

inhibition and judgement Premotor cortex involved in sensory guidance of movement Primary motor cortex area directly involved in producing muscle contraction Primary visual cortex receives the first visual information = Brodmann’s area 17, V1 see Striate cortex Procedural memory unconscious memory such as recall to catch a ball Process A general term describing any marked projection or prominence as in the mandibular process, in neurology the nerve process either Dendrite or Axon depending upon the direction of the NI. Projection fibres axons which connect the Cerebral cortex with the Brainstem or SC Proprioception sense of position of body parts Prosencephalon = forebrain Proximal closer to the axial skeleton (opposite of distal) Ptosis drooping - describing a dropping upper eyelid Pulvinar

a cushioned – posterior projection of the Thalamus over the medialseat and lateral geniculate bodies Putamen shell – larger lateral part of the lentiform nucleus – one of the basal ganglia Pure N a N which is either only sensory or motor not both (as in mixed N) Pyramidal system corticospinal and corticobulbar tracts which form a pyramid shape on the ventral surface of the MO Pyramidal tract corticospinal tract only Pyriform pear shaped – pyriform area of the olfactory cortex Quadriplegia = Ramus | Raphe

Reflex

Tetraplegia, paralysis of all 4 limbs branch pl. rami/branches - 2 main branches Ventral supplying all structures in front of the SC and Dorsal supplying all structures behind the SC - the Rami are mixed Ns seam – an anatomical seam in the midline – raphe nuclei of the reticular formation, in midline of the MO, Pons & MB referring to the Reflex arc of sensory impulse - going to the SC and causing a motor or efferent response

w/o imput from the brain Refractory period time b/n depolarization and repolarization, where the N cannot be restimulated in part to stop the impulse from traveling in both directions Repolarization restoration of the resting potential after transmission of a N impulse (see depolarization, polarization) 20

© A. L. Neill

INTRODUCTION

Resting potential

the charge difference across the cell membrane of the N created by ionic imbalance Reticular a net – as in the reticular formation of the brainstem Rhinal pertaining to the nose Rhinencephalon part of the components of the olfactory system Ridge Elevated bony growth often roughened. Root the segment(s) of srcin of the PN from the SN Rostral towards the nose Rostrum beak – recurved process of the Corpus Callosum Rubro red as in the red nucleus – rubrospinal tract Saccadic to jerk – as in quick jerky movements of the eyes when changing focus Sagittal an arrow, the sagittal suture is notched posteriorly, making it look like an arrow by the lambdoid sutures; the anatomical plane from anterior to posterior. Satellite attendant – satellite cells form a capsule around Ns Schwann cells

in ganglia cells supplying phospholipid coat - insulation to the axons to preserve the N impulse in the PNS - role of the oligodendrocytes in the CNS

Secondary visual cortex = Sensory

V2 perceives colour and form to feel pertaining to imput - which goes to the SC and then brain &/or reflex Short term memory that memory limited to several minutes of recall only Soma body - the main part of the neuron Somatic Somatosensory

bodily – denotes the viscera in neurology relating to information perveived through sensory receptors in the skin and muscles Spinal Cord (SC) Extension of the brain protected by the VC, PN come from here Spinal Nerve (SN) N coming directly from the SC not the brain Spine a thorn (adj. – spinous) descriptive of a sharp, slender process/protrusion. Splanchocranium the splanchocranium refers to the facial bones of theskull Splenium bandage – thickened post. extremity of the Corpus Callosum Stimulation events which lead to the formation of a N impulse Stimulus something in the environment which will cause a N impulse to be generated from the receptor Strabismus a squinting – constant lack of parallelism in the visual axes ie crossed eye(s) 21

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INTRODUCTION

Stratum Striate Striate cortex

layer – as in stratum zonal on the dorsal surface of the Thalamus striped striped rind = Brodmann’s area 17 = primary visual cortex = V1; CC on the Occipital lobe which receives 1s visual

information from the eyes via the Thalamus (has a white stripe w/in the cellular layer) Subcortical anything deep to or beneath the CC Subdural space space beneath the DM external to the AM Subiculum little layer - as in the thin layer of GM b/n Hp and parahippocampal gyrus Substantia gelatinosa a column of GM at the apex of the dorsal horn of the SC Substantia nigra dark substance - large nucleus in the MB with a high number of pigmented cells loss of cells in this area is related to Parkinson’s disease Sulcus long wide groove often due to a BV indentation –space b/n the gyri of the GM in the brain (pl – sulci) Superior temporal gyrus refines language interpretation such as recognizing “s” as a plural etc Supplementary motor area = SMA involved in complex motor functions such as 2 handed functions Supramarginal gyrus forms words form letters Sural pertaining to the lower leg Suture The saw-like edge of a cranial bone that serves as Synapse

Tapetum Tectum

joint between bones of the skull. to join - the gap at the joining of N and nerve process, N and N, process to process or N and muscle for transmission or inhibition of an impulse via neurotransmitters - presynaptic before the synapse (where the neurotransmitter is released) / post synaptic after the synapse (where the neurotransmitter is received). carpet – fibres from the corpus callosum over the lateral wall of the lat. Ven. roof – as in the roof of the MB

Tegmentum Tela choroidea

cover – dorsal portion of the Pons web membrane – vascular CT continuous with the PM which continues to the Choroid plexus Telodendria axon terminal branches Temporal refers to time and the fact that grey hair (marking the passage of time) often appears first at the site of the temporal bone. 22

© A. L. Neill

INTRODUCTION

Tetraplegia Thalamus

Tract Tractotomy Trunk

Uncus Uvula Vallecula Velate Ventral

see Quadriplegia inner chamber – functions are sensory and integrative – 2 egg-shaped masses of Ns – key relay station and filter of information to go to and not to go to the CC vertical columns of axons, generally myelinated in the SC &/or brain see Cordotomy when SNs join together as large combined large Ns to supply specific anatomical regions (e.g. BP) but again must re-organize to become PNs hook adj. Uncinate little grape – as in dorsal part of the cerebellum little valley – as in the fold on the inferior aspect of the cerebellum sail chest - to the front, used interchangeably with anterior, relating to the chest

Ventricle Vermis

little belly – as in ventricles of the brain filled with CSF worm – as in the vermis of the cerebellum – midline structure Wernicke’s area located in the Temporal lobe crucial for language and comprehension White matter N tissue which consists mainly of myelinated axons (see Grey matter)

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The A to Z of the Brain

Guide to Anatomical Planes and Relations This is the anatomical position. A = Anterior Aspect from the front Posterior Aspect from the back used interchangeably with ventral and dorsal respectively B = Lateral Aspect from either side C = Transverse / Horizontal plane D = Midsagittal plane = Median plane; trunk moving away from this plane = lateral flexion or lateral movement moving into this plane medial movement; limbs moving away from this direction = abduction; limbs moving closer to this plane = adduction E = Coronal plane F = Median C

D

E

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Anatomical Movements

Hipflexion

Hipextension

Hipabduction

Hipadduction

Hip lateral and medial rotation

Hip circumduction

Kneeflexion 26

Kneeextension © A. L. Neill


Foot dorsiflexion Foot plantar flexion

Foot inversion

Foot eversion

Foot normal position

Fingers extension

Fingers flexion

Forearm pronation Forearm supination

Fingersabduction

© A. L. Neill

Fingers adduction

Hand deviation radial/laterally ulna/medially

Thumbopposition

27

THE NERVOUS SYSTEM

The Nervous system The nervous system is made up of: the CNS = Brain + SC, the PNS = Ns exiting from the CNS - CRANIAL directly from the brain (12 PAIRS) and from the SC (31 PAIRS), the protective coverings of the tissue are made up of - connective tissue - the MENINGES of which there are 3 layers, the outer or DURA MATER and the inner often fused 2 layers THE ARACHNOID & PIA MATERS for the diffusions of CSF and blood around the Brain and SC, and boney coverings, the Skull around the brain and the vertebral column (VC) around the SC. In the PNS the Ns form 2 separate divisions the voluntary and the autonomic (ANS). The ANS is made up of the Sympathetic exiting from the thoracic region and Parasympathetic Ns, depending upon the region of the SC, and these nerves may travel with the PNs. PROTECTIVE COVERINGS

BONEY = SKULL

CENTRAL NERVOUS SYSTEM = CNS BRAIN

CONNECTIVE TISSUE = MENINGES

BONEY = VC CONNECTIVE TISSUE = MENINGES

28

PERIPHERAL NERVOUS SYSTEM = PNS ANS

CRANIAL NERVES (1-12)

SPINAL CORD = SC

SPINAL NERVES = SNs

© A. L. Neill


A

B

C

E

D

This brain is stripped of its normal meningeal coverings, showing cerebral cortex - grey matter.

A = superior view B = L lateral view C = R lateral view D = inferior view E = sagittal view

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THE NERVOUS SYSTEM

The Nerve Cells The basic functioning cell of the NS is the NEURON = NERVE CELL = N. Most are multipolar meaning that they have multiple dendritic (2) processes, which feed impulses into the nerve cell body (7). All Ns only have one axon (6), taking an impulse away from the cell body. There are 2 basictypes of Ns: - MOTOR Ns,which stimulate target organs and SENSORY Ns, which provide feedback about the target organs. Nerve cells when grouped together have a grey appearance and when seen in large collections are called GREY MATTER = GM, while their processes are often myelinated and appear white – so neural tracts are called WHITE MATTER = WM. In the brain the Ns are on the surface or cortex, except for some areas where collections of Ns may be seen deep in the brain tissue – nuclei (or ganglia). In the SC, the Ns are placed deep in the tissue in long columns.

1 2 3 4 5 6 7

nucleus and nucleolus dendrites neurilemma - protective myelin sheath from Schwann cells axon terminal branches / telodendria nodes of Ranvier axon and base of axon - axon hillock N cell body plasma with neurofibrils, Nissl bodies,

Golgi & ribosomes 8 mitochondria, presynaptic membrane 9 synaptic vesicles 10 neurotransmitter 11 synaptic cleft 12 postsynaptic membrane on dendrite or N cell body 13 myofibril of skeletal muscle 14 sarcolemma - cell membrane of the skeletal muscle cell 15 sarcoplasm - plasma of the skeletal muscle cell 16 subneural clefts 17 mitochondria 30

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THE BRAIN

Blood – Brain Barrier BBB Schema of Blood Vessel BBB in the neuroaxis of capillary BBB in the choroid plexus in ventricle The “Blood Brain Barrier” BBB prevents brain tissue from being exposed to various blood borne substances. This is achieved by a number of factors: the glial foot processes oncapillaries , the unique properties of the endothelial lining and components of the basement membrane. The filter also alters the components of the CSF fluid via the vessels in the choroid plexus and the choroid epithelium. Clinically this may prevent the neural tissue from the effects of oral and iv medications and toxins, requiring intrathecal injections. In certain pathologies particularly inflammatory ones the barrier can be compromised, causing oedema and other complications.

1 Medium sized cerebral BV 2 Pia Mater layer 3 Glia limiting membrane 4 Perivascular space

5 Foot processes of astroglia on capillaries 6 Neural tissue 7 BV lumen 8 Endothelial cell f = fenestration 9 Basement membrane 10 Glial tissue 11 Choroid epithelium

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2

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THE BRAIN

Blood Supply overview Brain Schema of the brain – coronal 1 2 3 4 5 6 7 8 9 10

Skull = boney covering Meningeal vein DM around the venous sinuses + communicating vessel External cerebral vein Brain – nervous tissue Choroid plexus Deep cerebral vein Extracranial vein Extracranial artery Meningeal artery

11 Superficial cerebral artery Spinal Cord Schema of the SC – transverse 1 2 3 4 5

Posterior spinal artery Radicular branches a = anterior / L = lateral / p = posterior Arterial vasocorona Lateral artery Anterior radicular artery

6 Branches of the superficial arterial network 7 Anterior spinal artery 8 Sucal artery = ant. spinal art. (lies in the sulcus of the SC) 9 Marginal zone (of Lissauer) - ALM tracts before synapse 10 Anterior horn = ventral motor horn 11 Deep spinal artery 12 Substantia gelatinosa - ALM Ns synapse point 13 Mediobasal column (of Clarke) - for sensory interneurons 14 Posterior horn = dorsal sensory horn 15 Skull = boney covering 16 Meningeal vein

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THE BRAIN

Blood Supply overview Spinal Cord Schema of the SC anterior surface C = cerebral region T= thoracic region L= lumbar region

1 Basilar artery 2 Vertebral artery 3 Radial artery of C5 4 Radial artery of C7 5 Anterior spinal artery 6 Lateral thoracic arteries 7 Artery of the lumbar enlargement Expanded on the one side at the level of T10 –L2

Spinal Cord Schema of the SC – deep and superficial arterial networks Note there are minimal anastomoses b/n these 2 different circulations This circulation as with the brain has end arteries and distally the tissue may be compromised. A deep arterial network – neural tissue supplied by anterior spinal artery B superficial arterial network

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1 2

3 4

C

5 T1

6

T

T12 7 L

A

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B

37

THE BRAIN

CEREBROSPINAL FLUID = CSF - circulation of fluid in and around the Brain & SC Lateral overview of ventricles Sagittal view of CSF circulation Definition – CSF bathes the Brain andSC, filtered from arterial blood by the Choroid plexus (27). Removing the blood proteins and cellular elements,it circulates through the ventricular system and subarachnoid space of the brain and SC and then is removed by the Arachnoid granulations (20) to the venous sinus systems around the brain. Blood in the perforating BVs (21) surrounding the neural tissue is also filtered via the BBB.

1 Frontal lobe

14 Pons

2 Anterior horn of lateral

15 Temporal lobe

ventricles 3 Body of the lateral ventricles -

16 3rd ventricle 17 Lateral fissure (Sylvian fissure)

4 Cerebral cortex

18 Interventricular foramen

5 Parietal lobe

19 Subarachnoid space

6 Posterior horn of the lateral ventricles

20 Arachnoid granulations

7 Occipital lobe 8 Cerebellum 9 Cerebral aqueduct (aqueduct of Sylvius) 10 4th ventricle with lateral aperture 11 Median aperture (foramen of Magendie) 12 SC 13 Lateral recess of 4th ventricle (foramen of Lushka) 38

21 Perforating veins 22 Pia/arachnoid mater 23 Transverse sinus 24 Cistern of the great cerebral vein* 25 Cerebral artery 26 Cerebral vein 27 Choroid plexus 28 Pituitary gland + stalk 29 Dura mater 30 Superior sagittal sinus *may sample CSF here © A. L. Neill


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39

THE BRAIN

Brain Development and Organization The Brain develops from ectoderm – the top germinal layer – cells form a tube – the neural tube which develops 3 bulges as shown and develop into the CNS. Additional cells excluded from the tube become the neural crest and form the components of the PNS. The brain continues to develop throughout adolescence and may do so throughout life, although neural tissue has a limited capacity to repair.

foramen magnum (exit from skull)

40

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PRIMARY BRAIN VESICLES

S ECONDARY DERIVATIVES BRAIN VESICLES

Cerebral Cortex

Telencephalon

Diencephalon

Basal Nuclei

Retina of the eye Thalamus Hypothalamus Neurohypophysis

Midbrain Superior colliculus

Metencephalon Myelencephalon

Spinal cord

© A. L. Neill

Pons Cerebellum

Medulla Oblongata

dorsal horn = sensory ventral horn = motor

41

THE BRAIN

The Brain and SC macroscopic structure The Brain places most of its neurons on the outer surface – cortex which gives the brain surface a grey colour hence it is – thegrey matter GM. The Ns are connected bytheir processes underneath mostly myelinated and hence white coloured fibre tracts – the white matter WM. The Ns of patterns the brainwhich are layed in multiple laminae/layers in particular can down be recognized and identified histologically with the NISSL stain. Particular cytoarchitechtural patterns have thus been identified and regionalized – the commonest scheme being the BRODMANN mapping of the CC. In many cases the structure has been found to relate to the function of these areas and so as well as naming the structure, a Brodmann number may also be listed. The “Brodmann area” is related to the arrangement of the Ns in the region but this may not always be directly related to the macroscopic appearance of the brain. The SC has its nerve cells on the inside, which are in long columns 2 in the front – ventral horns – and 2 in the back – dorsal horns. Connecting processes b/n the SC and the brain run up and down the SC outside the GM forming tracts of WM, and neurons are also found posteriorly sitting outside the main mass of the SC in small groups at each outlet dorsal root ganglia.

1 GM b = basal ganglia- deep GM - part of the Corpus Striatum / c = cerebrum / k = cerebellum / s = SC 2 WM c = cerebrum / k = cerebellum / s = SC 3 Space in the CNS filled with CSF in the c = cerebrum k = cerebellum s = SC (spinal canal) 4 Subarachnoid space 5 Sagittal sinus s = superior / i = inferior 6 Lateral ventricle 7 Third ventricle 8 Cerebral aqueduct

11 AM 12 PM

9 Fourth ventricle

13 Choroid plexus

10 DM

14 Arachnoid granulations

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5i

5S

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2C 1C

4C 6 7

13 3C

4 1B

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3S 9

2K

1S

1S 2S 12

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THE BRAIN

The Brain fibrous tracts coronal- view looking at the “face” sagittal – view looking from the side The Brain places most of its neurons on the outer surface – cortex which gives the brain surface a grey colour hence it is – thegrey matter GM. The Ns are connected bytheir processes underneath mostly myelinated and hence white coloured fibre tracts – the white matter WM. The fibrous tracts of the WM in the brain are of several types Association fibres = N tracts connecting one area to another of the same specialty of increasing complexity e.g. area primary visual cortex V1 to the secondary visual area V2 e.g. the perpendicular and uncinate fasciculi and the “short fibres” Commissural fibres = N tracts which cross from one side to the other in the cerebrum the largest of these is the Corpus Callosum (+ ant. & post. commissures) Projection fibres = N tracts which send fibres of one modality to an area of an other i.e. from the visual areas to the frontal areas for decision making processes to begin based on the visual information e.g. superior & inf. longitudinal fasciculi.

1 GM of the cerebrum = cerebral cortex 2 Association fibres of the cerebrum – WM – “short fibres” 3 Commissural fibres of the cerebrum - WM (Corpus Callosum) 4 Projection fibres of the cerebrum - WM 4i inferior longitudinal fasciculus / 4s superior longitudinal fasciculus

5 Gyrus 6 Sulcus 7 Longitudinal fissure 8 Lateral fissure / sulcus 9 Insula – GM of cerebrum deep to the lateral fissure 10 Thalamus 11 uncinate fasciculus 12 perpendicular fasciculus 44

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THE BRAIN

Dura Mater - DM = Hard Mother Outer layer of the Meninges Fixes the brain and limits movements supports the 2 inner coverings which contain the BS of the Brain. Continues down the SC to protect the neural tissue in this region as well. Composed of thick connective tissue Space b/n Skull and DM = EXTRADURAL SPACE (hence extra-dural haemorrhage) Space b/n DM and Pia – Arachnoid maters = SUBDURAL SPACE (hence sub-dural haemorrhage) The DM is pain sensitive and may be the cause of local headache or spinal pain or referred pain to structures associated with the exiting Ns.

1 Falx Cerebri – contains and prevents movement of the main cerebral hemispheres supports the superior sagittal sinus 2 Tentorium Cerebelli – separates the Cerebrum and the Cerebellum forming a roof over the cerebellum - supports the straight and transverse sinuses 3 Dura Mater – covering the SC – lumbar region 4 Zygapophyseal jt 5 Spinous process 6 Intervertebral disc 7 PLL (at the back of the VB) 8 Sinuvertebral N 9 SN 10 Sinuvertebral artery

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THE BRAIN

The Meninges and the Brain 1 Bone - Skull 2 Frontal sinus 3 DM 4 AM + Subarachnoid space 5 PM 6 SC 7 Dural sac of the SC (continuing on from the cranial cavity) 8 Subarachnoid space (b/n Cerebrum and Cerebellum) 9 CC – GM 10 Corpus Callosum 11 WM of the brain 12 Sagittal sinus i = inferior / s = superior 13 Falx cerebri 14 Arachnoid granulations

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THE BRAIN

The Meninges and the Spinal Cord (SC) Transverse view of the SC and coverings – cross-section Coronal view – cutting down the VC showing the SC and coverings.

1 SN 2

Nerve root (mixed N) d = dorsal root (pure sensory) v = ventral root (pure motor)

3 Denticulate lig. (from the PM) 4 DM 5 Outer layer of the AM 6 Subarachnoid space (b/n the intermediate layers of the AM) 7 Dorsal lig (from the AM) 8 PM 9 SC – GM d = dorsal horn v = ventral horn 10 Central canal 11 Filum terminale (PM) 12 Thoracic enlargement of the SC 13 Lumbar enlargement of the SC 14 SC termination – at L1/2 in adults 15 Spinal canal termination – at S2 16 Anterior spinal artery

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THE BRAIN

Neurological Assessment – HEADACHE DEFINITION: pain or discomfort b/n the orbits and Occiput arising from pain sensitive structures via Extracranial pain sensitive structures: The ear – inner & middle - also refers pain to C2 (2) The eye – orbit - also refers pain to C2/3 (3) The mouth – teeth & gums also refers pain to C4 (4) The nose - nasal mucosa, paranasal spaces also refers pain to C3 (3) The scalp – BVs & muscles also refers pain to C1 (1) Intracranial pain sensitive structures : Basal arteries Cortical veins & venous sinuses DM of the ACF and MCF – innervated by CN V1 (5) pain also referred to the forehead and temple & PCF - innervated by CN IX, X (6) – pain also referred to the back of the head and neck (suboccipital and upper cervical regions)

Note other structures e.g. the cervical VB and neck muscles may refer pain to the head and cause a “headache”

HISTORY: Associated features visual disturbances, vomiting + other Character

aching – dull / sharp, throbbing – stabbing

Duration & timing Frequency

hours / days / morning / evening acute – single, chronic – daily / wkly / mnthly intermittent - seasonal

Mode of onset

gradual, rapid

Precipitating factors coughing / exercising, hunger, medications / foods, menstruation / menopause noise / stress, posture changes / stooping Relieving factors

analgesics, lying down / sleeping

Severity

scale 1-5, bearable – able to read / unbearable – unable to do anything

Site

front / band around the head / back specific region – above the eye / around the temple

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THE BRAIN

HEADACHE – diagnoses ! = changes in !

progressive limb ! eye Head infectdeterioronset weak- moveinjury ion ation ness ments

pain type

consciousness

throbbing

-

-

-

±

quick

-

-

severe throbbing

±

-

-

-

quick

-

+

severe

-

-

-

-

quick

-

-

dull intermittant

-

+

-

-

slow

-

-

acute sharp

-

+

-

-

varies

-

-

severe

+

+

+

-

rapid

±

±

varies recedes

-

-

-

-

quick

-

-

severe

+

+

±

-

quick v +

severe

+

+

±

++

rapid

+

+

dull

+

+

±

-

slow

+

+

dull constant

+

+

-

-

slow

±

±

dull constant

+

+

-

-

slow

±

±

severe throbbing

-

-

-

-

slow

-

-

through the day

-

-

-

-

varies

-

-

dull

-

±

-

-

slow

-

±

sharp positional

-

±

±

-

varies

+

-

+

increases

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! neck recurr- nausea ± headache other stiffness vision ence vomitting location

±

face forehead

sinusitis

+

+

+

++

global

migraine

+

+

+

±

global

cluster headaches

-

+

+

-

frontal

halos around glaucoma objects

-

+

-

-

orbital

±

±

-

+

global

-

±

-

-

global

drugs/toxins vasodilators

+

±

-

++

global

haemorrhage

unilateral retrobulbar vision loss neuritis posttraumatic

meningitis focal encephalitis neurological acute / signs subacute impaired hydroceupward gaze phalus papilloe- intracranial dema Tm

+

±

-

++

global

±

+

-

+

global

-

±

-

+

global

-

±

-

+

global

papilloedema

benign intracranial hypertension

temple

stiff tender scalp arteries

temporal arteritis

frontal

situation

+

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++-

DX

-

+

-

-

-

++

-

-

+

-

-

+

-

+

-

band pattern

tension

headaches precipitates onset

need ocular impaired aids/glasses vision back and neck

upper limb cervical pain spondylosis 55

NEUROLOGICAL ASSESSMENT

NEUROLOGICAL SYMPTOMS changes in

site of control

balance conscious levels headache

CN VIII / middle ear global brain/ metabolic global brain / DM / neck / multiple sources

hearing mental

CN VIIIlobe middle frontal / ear endocrine motor SC / Brainstem / Cerebellum sensory SC / sensory CC smell CN I speech / swallowing CN IX-XII upper cervical Ns sphincters / continence Sacral Ns lumbar SC taste CN X, XII `` visual CN II-VI voice change CN X

NEUROLOGICAL EXAMINATION From head to toe CNs – see level CN section Conscious & higher functions – emotional state, memory, reasoning MOTOR Upper limbs – Trunk and lower limbs Sphincters Examine: power, tone, symmetry, reflexes, ROM SENSORY Upper limbs – Trunk and lower limbs Examine – pain, touch, pressure, proprioception, et mperature see the A to Z of Peripheral Nerves for details

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The UNCONSCIOUS PATIENT HISTORY Ask those around: Alcohol or drugs preceding the event ? medications ? Illness preceding the event – ± Epilepsy Sudden collapse jury ? ± Head in ± Limb twitching Assessment of conscious level (Glasgow coma scale) Assess EYE OPENING

SPONTANEOUS

TO SPEECH

TO PAIN via pressure to the supraorbital N

NON-RESPONSIVE Assess VERBAL RESPONSE ORIENTATED knows where they are CONFUSED

talks in sentences

WORDS

cannot form sentences but can form words

SOUNDS

can only make sounds

NONE

no response to questions

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OBEYS COMMANDS

LOCALISING MOVEMENT TOWARDS PAIN directional response to pain

FLEXING TO PAIN elbow flexing but no movement towards pain

EXTENDING TO PAIN extension of the elbow & spastic flexion of the wrist non-directional

Record assessments as 1-5 for each modality Always record the best result if there is variation Always record the upper limb result as this is more consistent 58

© A. L. Neill


APHASIA – acquired deficiency in language processing incorporating both production and comprehension, due to brain damage.

type Broca’s = expressive aphasia

area affected

ability to repeat speech

auditory comprehension

frontal cortex

++++

+++++

nonfluent laboured speech, slow disjointed sentences agrammatism

- but can learn and sing songs correctly (from the non. dom. CH)

fluent - nonsensical “jargon” paraphasic (substituting words which sounds the same) poor self correction

Wernicke’s* sup. temporal + = sensory gyrus of the aphasia = dominant CH receptive aphasia

fluency

Conduction = arcuate associative fasciculus dysphasia connecting Broca’s to Wernicke’s area

+

++++

often the result of a stroke, fluent paraphasic but with self correction

mixed transcortical

++

+

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fluent self correction of grammar + syntax only

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oftentheresultofhead injury or tumour, fluent – circumlocution because cannot recall the names of things

gyri global anomic = amnesic dysphasia

global ++ parietal + temporal lobes & their connections

* note is not Wernicke’s encephalopathy

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THE BRAIN

Blood Vessels and the Meningeal layers of the Brain 1 scalp vein 2 scalp – skin covering the skull 3 middle meningeal vessels a=anterior / m=middle / p=posterior branches 4 Frontal bone 5 dura mater e= endostial / m= meningeal layers 6 Parietal bone 7 transverse sinus (R/L) 8 Occipital bone 9 superior sagittal sinus / v= venous lacuna 10 arachnoid granulations 11 emmisary veins 12 cerebral veins s=superior /sp=superficial branches 13 arachnoid mater p with pia mater (often fused) 14 cerebellum 15 diploic vein 16 frontal sinus

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THE BRAIN

Venous sinuses the Meningeal layers of the Brain 1 scalp vein

20 optic chiasma

2 scalp – skin covering the skull

21 carotid artery

3 middle meningeal vessels a=anterior /m=middle / p = posterior branches

23 hypophysis and stalk (infundibulum)

4 Frontal bone 5 DM e = endostial / m = meningeal layers 6 Parietal bone 7 transverse sinus (R/L) 8 Occipital bone

22 sphenoparietal sinus

24 CNs – 24-3 CN III / 24-6CN VI / 24-4 CN IV/ 24-5 CN V 25 petrosal sinus s=superior/ i=inferior

9 superior sagittal sinus / v = venous lacuna

26 straight sinus 27 tentorum cerebelli e=edge inserted b/n cerebrum & cerebellum

10 arachnoid granulations

28 great cerebral vein

11 emmisary veins

29 basilar plexus

12 cerebral veins s=superior

30 dorsum sella

/sp=superficial branches 13 arachnoid mater with pia mater (often fused)

(DM removed) 31 cavernous sinus

14 cerebellum

32 orbital plate (of the frontal bone) ACF

15 diploic vein

33 crista galli

16 frontal sinus 17 cerebrum – postcentral gyrus 18 falx cerebri 19 olfactory bulb and tract

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THE BRAIN

Brain arteries - Overview The brain is an end organ in that once past a central anastomotic ring of vessels, the circle of Willis – all supply tothe distal tissue is a single supply. Any blockage of the BV distal to that arterial circle will die, making the Brain a great energy consumer sensitive to any regional deprivation of blood. Overall the brain as a whole cannot be deprived of arterial blood for longer than 10 sec to any partic. area - 20% of the CO goes to the brain – brain is 2.5kg or <2% of the body weight.

1 Anterior spinal art. 2 Vertebral art. – paired 3 Post. Inf. Cerebellar art. 4 Ant. Inf. Cerebellar art. 5

Basilar artery – from the fusion of the paired vertebrals

6 Pontine branches 7 Post. Cerebral art. (branch pierced by CN III) 8 Circle of Willis = arterial circle , 9 Middle cerebral art (branch b/n. frontal & temporal lobe) 10 Ant. Cerebral art. (branch under optic chiasma) 11 Cerebellar arteries

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THE BRAIN

The Veins and Venous drainage of the BRAIN Overview On the surface of the brain there are many BVs which drain into a series of sinuses – endothelial lined channels b/n the 2 layers of the DM. They anastomose extensively and have no valves relying on gravity, cranial pressure and head movements for drainage. Superficial vessels drain to the superior sagittal sinus (1s) and deeper vessels drain to the straight sinus (4). The eyeball and facial areas drain to the cavernous sinus (8) and may bring infection into the cranial cavity.

1 Sagittal sinus i=inferior / s = superior 2 Connecting anastomosing veins 3 Deep posterior cerebral veins 4 Straight sinus 5 Transverse sinus 6 Sigmoid sinus (s-shaped) 7 Petrosal sinus i =inferior / s = superior 8 Cavernous sinus 9 Internal jugular vein

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THE BRAIN

Cranial Venous Sinuses The venous supply of the brain consists of a number of sinuses - or lakes of blood protected from the brain tissue by the DM. Unlike other veins in the body, they have no muscle or valves in their walls. Arachnoid granulations feed CSF into this system, which then drains to the jugular veins. Flow is determined by pressure w/in the cranial cavity – a closed box. CSF, gravity and arterial pressure affect this and flow may be very slow and on occasions is bidirectional.

Cavernous Sinus Coronal section, Looking into the sinus posteriorly One of the most complex sinuses is the Cavernous sinus. Through this lake of slow moving venous blood, air, arteries, brain and glandular tissue and CNs traverse, making this site particularlydangerous for infection and/or neoplastic spread.

1 pituitary gland = hypophysis 1a anterior lobe 1i infundibulum = stalk 1p posterior lobe 2 third ventricle 3 Optic N = CNII

9 Trigeminal N =CN V 9-1 CN V1 9-2 CN V2 10 foramen ovale 11 Abducens N = CN VI 12 internal carotid artery 13 carotid sympathetic

3c chiasma 3n nerve 4 cerebral arteries – branches 4a anterior 4m middle 4p posterior 5 internal carotid artery

nerve plexus 14 opening to nasal cavity 15 sphenoidal air sinuses 16 body of the sphenoid 17 DM – dura mater e = endostial layer m = meningeal layer 18 cavernous sinus = filled with venous blood 19 cerebral cortex 20 AM -arachnoid mater 21 subarachnoid space 22 PM = pia mater 23 diaphragma sella

6 communicating arteries 6a anterior 6p posterior 7 Occulomotor N = CN III 8 Trochlear N = CN IV 68

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Sagittal venous sinuses – Superior and Inferior Superio-lateral looking into the head from above and laterally

1 CNs – 1-3 CN III /1-6CNVI / 1-4 CNIV/ 1-5 CNV 2 emmisary vein 3 scalp – skin covering the skull 4 DM e= endostial / m = meningeal layers 5 sagittal sinus / s = superior / i = inferior 6 falx cerebri 7 hypophysis i = infundibulum (stalk) 8 crista galli 9 petrosal sinus s = superior/ i = inferior 10 tentorum cerebelli e=edge 11 transverse sinus 12 straight sinus 13 great cerebral vein 14 cerebral artery a=anterior /m= middle / p= posterior branches 15 communicating artery a = anterior / p = posterior branches 16 internal carotid artery 17 frontal air sinus 18 trigeminal ganglion (from CNV) 19 middle meningeal vessels a = anterior /m = middle / p = posterior branches 20 greater superficial petrosal N 21 cerebral aqueduct (aqueduct of Sylvius) 22 midbrain See the website for more details on the Blood Vs and CNs relationships. 70

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THE BRAIN

Circle of Willis = Cerebral arterial circle Arterial vessels to supply the cerebrum arise from the inferior surface of the brain via the internal carotid arteries which enter the cranium via the carotid canal and the anterior surface of the SC via the Basilar artery from the fusion of the 2 Vertebral arteries.These 3 BVs form an anastomotic arterial ring – the circle of Willis - from which branches arise to supply the cerebrum. Because of its structure, supply can be continued despite the blockage of any 1 or 2 of the individual contributors, provided it is not acute. However distal to the ring this si not the case.

1 Anterior cerebral 2 Anterior communicating 3 Ophthalmic 4 Internal carotid 5 Medial striate (branches) 6 Midfdle cerebral 7 Lateral striate (branches) 8 Anterior choroid 9 Posterior communicating 10 Posterior cerebral 11 Superior cerebellar 12 Posterior choroid 13 Basilar

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THE BRAIN

The Brain – Macroscopic Components The brain lies in the cranial cavity –the skull - consists of the CEREBRUM, CEREBELLUM, MIDBRAIN, and HIND BRAIN which leads to the SC. The CEREBRUM overlies most of the brain and consists of 5 lobes named according to the bones which they underly, see the A to Z of the Head & Neck

, and the hidden grey matter the INSULA. B/n the brain and the skull are the meninges which act as protective coverings, limit the movement of the brain w/n theskull, support the BS and CSF and filter material to and from the brain. The outer GM is arranged as a series of folds to maximize the surface area: the GYRI the convex folds and grooves SULCI (may also be called fissures), named according to their anatomical position on the brain. Brodmann numbers have also been assigned to these areas, particularly on the CC which relate the grey matter to brain functions, they often span gyri and do not directly correlate to the anatomical divisions of the brain. Generally information flows from the back of the brain– primarily the sensory areas – via a series of tracts of WM – nerve processes - to the front where it is integrated and processed, resulting in decisions, planning or other higher functions. FRONTAL LOBE for thinking, planning, decision making & motor execution II PARIETAL LOBE for somatosensory perception -integration of visual, proprioceptive and spatial information. III TEMPORAL LOBE for language, auditory perception, memory & emotion

IV OCCIPITAL LOBE for vision 1 CN V1 opthalmic division Inferior Lateral Posterior

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THE BRAIN

The Brain – Macroscopic Components cont 1 Frontal lobe 2 Central Sulcus = Rolandic fissure 3 Parietal lobe 4 Parietal – occipital sulcus 5 Occipital lobe 6 Cerebellum 7 SC coming from the Brainstem 8 Temporal lobe 9 Lateral fissure = Sylvian fissure 10 Central Sulcus = Central fissure 11 Cerebral hemisphere = CH 12 Cerebellar hemisphere 13 Posterior lobe of the cerebellum 14 Vermis 15 Folia = small gyri and sulci of the cerebellum 16 Pons 17 Infundibulum (of the pituitary removed)

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THE BRAIN

Cerebral gyri and sulci Inferior view – looking up at the cerebrum Lateral – looking at the side of the cerebrum Median = Midsagittal - looking at the middle plane The labeling of the fissures, gyri and sulci are often duplicated. The most common duplications are listed here. Gyri can also be labeled using a Capital letter to designate the lobe and a number to show its position in the lobe. Sulci are labeled the same way only with a small letter –e.g. T1 = first or superior temporal gyrus –the corresponding sulcus = t1. However several of these large folds may cross the lobe or may have different names along their length. The commonest names and duplications are listed below. 1g-5g = orbital gyri 1s-3s = orbital sulci

1g gyrus rectus, straight gyrus F4

10g lingual gyrus 05

2g medial orbital gyrus F5

10s hippocampal sulcus t5

3g anterior orbital gyrus F3

11g occipitotemporal gyrus

4g posterior orbital gyrus F3 5g lateral orbital gyrus F3 1s medial orbital sulcus f4 2s H-shaped orbital sulcus f3 3s lateral orbital sulcus f3

10l hippocampal lobule T5

inferiotemporal gyrus T3 12g lateral occipitotemporal gyrus fusiform gyrus occipitotemporal gyrus T4 13g inferior-occipital gyrus O3 14g cingulate gyrus F5/P5

6f rhinal fissure (b/n frontal & temporal lobes)

15f Sylvian fissure = lateral sulcus

7g gyrus ambiens T5

16g precentral gyrus 1o motor area F3

7s collateral sulcus t4 8g lunate gyrus = uncus T5 8s sulcus semilunaris t5

16s central sulcus 17g postcentral sulcus 1o sensory area P1

9g medialoccipitotemporal gyrus 18g paramarginal gyrus P3 = parahippocampal gyrus O5/T5 19g angular gyrus 78

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THE BRAIN

Cerebral gyri and sulci cont 20g superior temporal gyrus T1 21g middle temporal gyrus T2 22s Occipitotemporal sulcus b/n Occipital & Temporal lobes 23s Calacarine sulcus (meets 22s) 24g Hippocampal gyrus T5 25

Cuneus O1

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Precuneus O2

27g Cingulate gyrus 27s Cingulate sulcus 28

Corpus callosum

28s Corpus callosum sulcus superior-anterior projection of the CC = frontal pole posterior part of the CC = occipital pole inferior – anterior projection of CC temporal pole cingular gyrus = small GM just above corpus callosum dentate gyrus = posterior layered part of the hippocampal gyrus undergoes neogenesis in the adult – for new memories ? fornicate gyrus = cingulate + parahippocampal gyri (fornix) note there are also 5 gyri in the Insula I1-5 i = pars operculus ii = pars triangularus iii = pars orbicularis all parts of F3 = inferior frontal gyrus

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THE BRAIN

Brain Median view – midsagittal This dissection halves the brain through the longitudinal sulcus Moving rostrally from the most caudal gyrus – the lingual, cuneus, precuneus, postcentral, paracentral, marginal (medial frontal gyrus) and straight gyri (gyrus rectus) face into this sulcus from each CH. The pons, cerebellum, thalamus,optic chiasma and midbrain are bisected. The pituitary is not, although it is midline.

1 Gyrus rectus – straight gyrus (of the frontal pole)

17 Parieto-occipital sulcus

2 Optic structures = CN II c = chiasma / n = nerve r = radiation

19 Post-central gyrus (parietal lobe)

3 Pituitary gland

20 Central sulcus 21 Paracentral gyrus = Precentral gyrus

4 IVth ventricle 5 Tuber cinereum 6 Mammillary body 7 Pons 8 Olive

18 Precuneus (parietal lobe)

22 Medical frontal = marginal gyrus 23 Thalamus and intermediate body (connecting the 2 sides)

9 Hindbrain 10 Spinal canal (from aqueduct)

24 Fornix

11 Temporal lobe (contralateral)

26 Cingulum

25 Septum pellucidum

12 Cerebellum – vermis

27 Minor gyri and sulci in the frontal lobe

13 Pinal body + Great cerebral vein

28 Corpus callosum s = splenium / r = rostrum /

14 Lingual gyrus (Occipital lobe)

g= genu 29 Lamina terminalis

15 Calcarine sulcus 16 Cuneus (Occipital lobe) 82

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THE BRAIN

Cerebrum – sections Transverse section (guide) – coronal sections i-iv i = at the level of the anterior commissure ii = behind the anterior commissure iii = through the mammillary bodies iv = through the thalamus

1 Longitudinal fissure dividing the 2 cerebral hemispheres 2 Corpus callosum g = genu s = splenium 3 Lateral ventricle ah = ant. horn / ph = post horn 4 Putamen (part of basal nuclei) 5 Globus pallidus 6 Capsules - i = internal / e = external 7 Thalamus - s = subthalamic nuclei / n = nuclear groups 8 Tela choroidea + choroid plexus 9 Fornix c = columns / x = crura 10 Claustrum 11 Septum pellucida c = cavity / l = lamina / v = vein 12 Caudate nucleus

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THE BRAIN

Cerebrum – sections coronal i = at the level of the anterior commissure ii = behind the anterior commissure

1 Longitudinal fissure dividing the 2 CH 2 Corpus callosum g = genu s = splenium 3 Lateral ventricle ah =ant. horn / ph = post horn 4 Putamen (part of basal nuclei) 5 Globus pallidus 6 Capsules – i =internal / e = external 7 Thalamus s = subthalamic nuclei / n = nuclear groups 8 Tela choroidea + choroid plexus 9 Fornix c = columns / x = crura 10 Claustrum 11 Septum pellucida c = cavity l = lamina / v = vein 12 Caudate nucleus 13 Cingulate sulcus 14 Longitudinal fasciculus s = superior 15 Operculum 16 Lateral sulcus 17 Insula 18 Uncinate fasciculus 19 Collateral sulcus 86

20 Optic tract 21 Anterior commissure 22 Corona radiata 23 Third ventricle 24 Precentral gyrus 25 Temporal gyri s = superior / m = medial i = inferior 26 Amygdaloid complex 27 Hippocampus 28 Fusiform gyrus 29 Parahippocampus (gyrus) 30 Mammillary body 31 Base of hypothalamus 32 Substantia nigra 33 Gyrus occitpitotemporalis medialis

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THE BRAIN

Cerebrum – sections coronal iii = through the mammillary bodies iv = through the thalamus

1 Longitudinal fissure dividing the 2 CH 2 Corpus callosum g = genu s = splenium 3 Lateral ventricle ah = ant. horn / ph = post horn 4 Putamen (part of basal nuclei) 5 Globus pallidus

20 Optic tract 21 Anterior commissure 22 Corona radiata 23 Third ventricle 24 Precentral gyrus 25 Temporal gyri s = superior m = medial / i = inferior 26 Amygdaloid complex

6 Capsules – i = internal / e = external 7 Thalamus s = subthalamic nuclei / n = nuclear groups 8 Tela choroidea + choroid plexus 9 Fornix c = columns /

27 Hippocampus 28 Fusiform gyrus 29 Parahippocampus (gyrus) 30 Mammillary body 31 Base of hypothalamus 32 Substantia nigra 33 Gyrus occitpitotemporalis medialis

x = crura 10 Claustrum 11 Septum pellucida c = cavity l = lamina / v = vein 12 Caudate nucleus 13 Cingulate sulcus 14 Longitudinal fasciculus ii s = superior iv 15 Operculum 16 Lateral sulcus 17 Insula 18 Uncinate fasciculus 19 Collateral sulcus 88

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THE BRAIN

Brain sagittal section - off centre This section shows the Corona Radiata with the fibres from the related GM and N tracts projecting into it.

1 Olfactory CN I t = tract / a = trigone 2 Optic tract Corpus callosum g = genu / r = rostrum 3 Crus Cerebri 4 Striae terminalis 5 pyramidal bundles in the Pons 6 Pyramid 7 Olive 8 Hindbrain / SC 9 Hippocampus w/in the Dentate gyrus 10 Cerebellum 11 Optic radiation –in the Corona Radiata 12 Superfical longitudinal fasciculus (of Corpus Callosum) 13 Corona Radiata 14 Central sulcus 15 Internal capsule + medial wall of putamen – (part of the corpus striatum) 16 Anterior commissure 17 Orbital surface of the frontal lobe 18 Gyrus rectus / straight gyrus

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THE BRAIN

Brain – superior to Globus Pallidus transverse section - viewing it from above see also Cerebrum Sections transverse section (deeper level at the mammillary bodies) This slice through the brain shows the development of the internal GM of the cerebrum: head of the caudate nucleus (16), the thalamus (13), the pulvinar (13p), striate body and its contents (5,6,7,9& 14) and projection fibres - the optic radiation (10) and tapetum (11).

1 Longitudinal fissure 2 Middle frontal gyrus 3 Corpus callosum g = genu / s= splenium 4 lateral ventricle a = anterior horn / p = posterior horn 5 Septum Pellucidum – cavity 6 External Capsule 7 Claustrum 8 Insula 9 Internal Capsule g = genu / p = posterior limb 10 Optic radiation 11 Tapetum 12 junc of Posterio-occipital and Calcarine sulci 13 Thalamus (p= pulvinar) 14 Lentiform nucleus p = putamen 15 fornix – columns 16 Caudate nucleus 17 Cingulum 18 Middle Cerebral artery 19 Calcarine Sulcus 20 Fimbria

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THE BRAIN

Anterior Commissure coronal section – viewing it from the front transverse section - viewing it from above This is a major communication pathway b/n the 2 CH - anterior to the columns of the fornix and connecting the 2 temporal lobes, olfactory tracts and amygdaloid bodies. It is part of the neospinothalamic tract for pain, and is inferior to and smaller than the Corpus Callosum - 10X larger. It has been implicated in gender studies because of its increased size in homosexual men compared to heterosexual men (34%) and heterosexual women (20%).

1 longitudinal fissure 2 Corpus callosum g = genu / r = rostrum

17 septum pellucidum 18 globus pallidus 19 striae arteries

3 caudate nucleus 4 internal capsule 5 lentiform nucleus p = putamen 6 external capsule 7 anterior commissure 8 uncinate fasciculus – last WM to mature in the human

20 amygdaloid bodies 21 infundibulum 22 root of the Optic N CN II 23 lateral ventricle i =inferior horn 24 Anterior perforating substance 25 pons (part of the limbic system) 26 crus cerebri 9 inferior longitudinalfasciculus 27 lamina terminalis = occipitotemporal fasciculus (continuous with 2g) 10 insula 28 subcallosal gyrus = 11 corona radiata –base of paraterminal gyrus (continuous with 27) 12 habenular nuclei (part of the diencephalon) 13 pineal body /gland 14 thalamus 15 claustrum (connecting basal nuclei – suspectedreceptors of hallucogens LSD) 16 fornix – columns of 94

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THE BRAIN

Basal Ganglia = Basal Nuclei Coronal plane - looking in from the anterior Sagittal - looking in from the side The Basal ganglia are connected groups of GM deep nuclei - in the brain in the diencephalic region - around the thalamus and hypothalamus. Named primarily because of their relationship to the lateral and 3rd ventricles they act as further modifiers b/n the thalamus and the CC. They are the beginning of the change of the GM from an outer rim in the CC to the central core it becomes in the SC. They lie in the 3 divisions of the thalamic regions. A = Ep it ha la mu s C = Thalamus C = Hypothalamus (rostral) + Subthalamus (caudal)

1 2 3 4 5 6 7

Corpus callosum Caudate nucleus Lateral ventricle Choroid plexus Thalamus Putamen Globus pallidus

8 Zona incerta 6+ 7+ 8 = Lentiform nucleus 9 Supraorbital nucleus 10 Optic tract + chiasma 11 Subthalamic nuclei = nucleus of Luys 12 Ventromedial nuclei of the hypothalamus 13 Nucleus tuberus 14 Pituitary gland=Hypophysis a = anterior lobe adenohypophysis p = posterior lobe neurohypophysis 96

15 Infundibulum (of the pituitary gland) 16 Third ventricle 17 Interthalamic adhesion 18 Paraventricular nucei 19 Septum pellicidum 20 Fornix 21 Transverse cerebral fissure 22 Periventricular nuclei 23 Mammillary nuclei 24 Hypothalamic nuclei 25 Dorsomedial nuclei 26 Pineal body

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?? ?

Brain Stem = Midbrain + Pons + Medulla Oblongata Anterior surface Lateral view All CNs except CN I, IV & XI arise from the anterior surface of the brainstem.

The SC begins at the inferior end of the Brainstem, and cerebrum arises superiorly. 1-12 labels the CNs - subcategories indicate the parts thereof

1 CN I - b= bulb / f = fibres dropping through the sup. concha of the nose / l = lateral striae / t = tract / ! = trigone 2 CN II - c= chiasma or crossing (50%of fibres cross to the other CH) / n = nerve / t = tract . 3 CN III 4 CN I 5 CN V 6 CN VI 7 CN VII + nervus intermedius of Facial N 8 CN VIII –both parts 9 CN IX travels with CN X 10 CN X 11 CN XI arises from the SC 12 CN XII arises superior to CN XI but leaves the cranium inferiorly 13 Crus cerebri – part of the midbrain 14 Geniculate body l = lateral / m = medial 15 Pulvinar (posterior nuclei in the Thalamus) 16 Middle cerebellar peduncle 17 Inferior cerebellar peduncle 18 C1 ventral roots 98

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THE BRAIN

Brain Stem = Midbrain + Pons + Medulla Oblongata Cont Anterior surface Lateral view

19 Pyramid 20 Decussation of pyramids 21 SC 22 Cerebellar flocculus 23 Olive crossed by ant. ext. arc fibres 24 Pons 25 Perforating substances a= anterior / p= posterior 26 Mammillary body 27 Tuber cinerum 28 Infundibulum (of pituitary gland) 29 Ant. Perforating substance 30 Inf. surface of frontal lobe 31 Frontal pole 32 Longitudinal fissure 33 Caudate nucleus 34 Corona radiata (base of) 35 Lateral leminiscus 36 Superior cerebellar peduncle 37 Arbor vitae (of the cerebellum) 38 Cuneate tubercle 39 Gracile tubercle 40 Spinocerebellar fasciculus a= anterior / p = posterior 41 Olive tract = circumolivary fasiculus 42 Gyrus rectus = straight gyrus 43 Anterior commissure 44 Striate anastomoses

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THE BRAIN

Brainstem - arterial supply Lateral view

1 pontine cerebral art. 2 inferior colliculus 3 cerebral aqueduct 4 inferior quadrigeminal art. 5 superior vermis of cerebellum 6 superior cerebellar art. 7 dentate gyrus 8 anterior inferior cerebellar art. 9 cerebellar flocculus and nodulus 10 4th ventricle 11 posterior inferior cerebellar art. 12 central canal 13 posterior spinal art. 14 veretbral art. (paired vessels) 15 anterior spinal art. 16 paramedian art. 17 cuneate and gracile nuclei 18 inferior olivary nuclei 19 pons 20 basilar art (unpaired – fusion of the vertebrals) 21 posterior communicating art. (part of the circle of Willis)

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Cerebral arteries The arteries supplying the cerebrum consist of 3 paired branches arising from the arterial circle or Circle of Willis: the anterior, middle and posterior cerebral arteries. Their supply corresponds roughly although not absolutely with the cerebral lobes. There areanastomising no branches between thesesystem arteries,and in if contrast to the extensive in the venous blocked, the distal tissue generally dies. The brain is very sensitive to any deprivation of oxygen and will die of deprived for oxygen completely for longer than 1 min in normal circumstances. Lowering the temperature, releasing intracerebralpressure, rapid dissolving of the intravascular blockage (usually a clot) all help to reduce the permanent damage of such an event. Brain tissue has limited capacity to repair or regenerate its tissue. A = cerebral tissue supplied by the anterior cerebral artery and its branches M = cerebral tissue supplied by the middle cerebral artery and its branches P = cerebral tissue supplied by the posterior cerebral artery and its branches

1 Anterior cerebral artery b = branches 2 Anterior communicating artery 3 Middle cerebral artery b = branches 4 Posterior cerebral artery b = branches / c = calcarine branch / o = occipital branch 5 Brainstem 6 Corpus callosum g = genu / s = splenium 7 Anterior perforating substance 8 Thalamus

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Brodmann’s Maps of the Cerebral Cortex Lateral Mid-Sagittal – median Inferior of the frontal lobe Brodmann areas were srcinally defined and numbered by Korbinian Brodmann in 1909 based on the organization cytoarchitecture and histology of Ns in the CC. The numbers start from the central sulcus and move outwards. Many of the areas Brodmann defined based solely on their neuronal organization have been correlated closely to diverse cortical functions, but they donot always correlate with the macroscopic anantomy of the cerebral cortex nor do all the areas have a functional correlation as seen in the following table. There has been much discussion about the boundaries and their correlations. This is the most widely accepted mapping. FRONTAL LOBE OCCIPITAL LOBE PARIETAL LOBE TEMPORAL LOBE

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BRAIN IMAGES

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BRAIN IMAGES

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CT IMAGING

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HIGHER CEREBRAL FUNCTION assessment COGNITIVE SKILLS tested

language pattern hesitant fluent can simple orders be followed

hold up your arms! can simple objects be named –

what is this? (a ball)

Dominant CH Disorders Note L hemisphere is Dominant in R-handed People dysphasia receptive / expressive receptive dysphasia nominal dysphasia

can the patient read words correctly ? dyslexia can the patient write words correctly ? dysgraphia can the patient calculate simple tests ? dyscalculia can the patient pick the object asked in agroup of objects?

can the patient find their way around their surroundings ? can the patient dress them selves ? can the patient draw shapes ?

please draw a square / circle / clockface

agnosia geographia agnosia dressing apraxia constructional apraxia

MEMORY TESTED can the patient copy a beat with their fingers?

immediate memory loss

can mealthe ? patient describe their illness and last

recent memory loss

can the patient remember their recent past before the illness ?

remote memory loss

can the patient remember the items on a tray after it is removed ?

visual memory loss

REASONING & PROBLEM SOLVING

set small problems / ask about ability to receive the right change

EMOTIONAL STATE

anxious / depressed flat / apathetic / inappropriate disinhibited / slow in speech or movement c

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Cerebrum - Major Anatomy Lateral and Superior CEREBRUM – covered in GM with 4 major lobes, 4 major lobes of the Brain and a covered area of GM - the Insula or 5th lobe 1 FRONTAL LOBE 2 PARIETAL LOBE 3 OCCIPITAL LOBE 4 TEMPORAL LOBE 5 INSULA Separated by major fissures or sulci A central sulcus = Rolandic fissure b/n the frontal and parietal lobes B parieto-occipital sulcus C preoccipital notch D

lateral sulcus = Sylvian fissure b/n the temporal and the frontal +parietal lobes E stem of the lateral sulcus L longitudinal suclus = longitudinal fissure b/n the R and L CH further subdivided w/n the lobes by minor sulci j lunate sulcus h transverse occipital sulcus i inferior temporal sulcus l intra parietal sulcus k associated rami of the lateral sulcus GM either side of the lateral fissure = Opercula, overlies the covered GM of the brain = Insula = Island of Reil g = gyrus bulge in the brain s = sulcus / fissure if large = infolded section b/n the gyri 1Ag pre-central gyrus MOTOR 2Ag post central gyrus SENSORY 2Ig inferior parietal gyrus (lobule) 2Sg 1Sg 1Fg 1Ig 4Dg 114

superior parietal gyrus (lobule) superior frontal gyrus mid frontal gyrus inferior frontal gyrus 4Ig inferior temporal gyrus superior temporal gyrus 4Mg mid temporal gyrus © A. L. Neill


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Cerebrum – Insula and Operculum Lateral Most of the GM of the cerebrum is superficial and divided into 4 lobes named according to the bones which overlie them - but a “5th” lobe is buried deep to the Lateral fissure - the Insula (island) the GM overlying this Insula GM is the Operculum

1 Operculum -(insula lying deep to this GM) – partially in the frontal, parietal and temporal lobes 2 Insula (operculum cutaway) showing fibres of the corona radiate going to the GM on the surface See website for more details on the Cerebrum and Cerebellum.

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Operculum

Insula

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Cerebrum Inferior view - Cerebellum removed CEREBRUM – a highly folded cap of neural tissue with the outer N cells (GM), sitting in the anterior and middle cranial fossae. Arranged into 4 major lobes on the surface, the cerebrum is responsible for most of the “executive” decisions of the body and mind. Many of the CNs can be seen emerging from the brainstem inserted into the undersurface concavity of the cerebrum, and continuing on to become the SC.

1 Olfactory bulb and tract – CN I 2 Optic nerve, chiasma and tract CN II 3 Stem of the lateral sulcus 4 Collateral sulci 5 Preoccipital notch 6 Occipito-temporal sulcus 7 Lunate sulcus 8 Occiptial pole 9 Branches of the occipital sulcus 10 Frontal pole (of frontal lobe) 11 Gyrus rectus = straight gyrus 12 Orbital sulci 13 Parahippocampus 14 Gyrus occipitotemporalis medialis 15 Lingual gyrus 16 Cingulum 17 Longitudinal Sulcus 18 Cerebral aqueduct + periductal GM 19 Crus cerebris 20 Mammillary body 21 Infundibulum ( of the pituitary) 22 Anterior perforating substance 22 Uncus 118

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Cerebellum – Little Brain views from the back and side – posterio-lateral in the middle through the 4th ventricle – mid-sagittal median plane (see also Cerebrum outer surfaces posterior) Responsible for most “unconscious” motor movements: coordination, posture and balancing of the motor system, affected by sedatives and alcohol. Lying under the Occipital lobes the cerebellum is made up of 2 small hemispheres separated by a small wormlike bridge the Vermis, with small transverse folds = folia as opposed to the large folds = sulci + gyri of the cerebrum, and 3 lobes as opposed to the 5 (4+1) of the cerebrum.

1 2

Vermis superior, middle and inferior sections Anterior lobe (small)

15 Middle cerebellar peduncles 16 Superio cerebellar peduncles

3

Primary fissure

4

Posterior lobe (largest lobe)

17 Fourth ventricle

Folia - fine folds of the cerebellum

19 Cerebral aqueduct

SC Flocculonodular lobe (= 21 + 24)

21 Flocculus 22 Secondary fissure

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6 7 8

Medulla oblongata

9

Pons

10 Arbor vitae of the cerebellum

18 Crus cerebri 20 CN V

23 Posterior notch 24 Central nodule 25 Folds of the vermis (cut through) 26 Uvula – inferior process

11 Cerebellar cortex 12 Dentate nuclei

of the vermis 27 Cerebellar tonsil

13 Choroid plexus

28 Vallecular cerebella

14 Inferior cerebellar peduncles

29 Posterior median Sulcus of the SC

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Cerebellum – Little Brain views from the back and side – posterio-lateral in the middle through the 4th ventricle – mid-sagittal median plane (see also Cerebrum outer surfaces posterior) Responsible for most “unconscious” motor movements: coordination, posture and balancing of the motor system, affected by sedatives and alcohol. Lying under the Occipital lobes the cerebellum is made up of 2 small hemispheres separated bya small wormlike bridge the Vermis,with small transverse folds = folia as opposed to the large folds = |sulci + gyri of the cerebrum, and 3 lobes as opposed tothe 5 (4+1) of the cerebrum.

1 Vermis superior, middle and inferior sections 2 Anterior lobe (small)

17 Fourth ventricle 18 Crus cerebri 19 Cerebral aqueduct

3 Primary fissure 4 Posterior lobe (largest lobe) 5 Folia - fine folds of the cerebellum 6 SC 7 Flocculonodular lobe (= 21 + 24)

20 21 22 23 24 25

8 Medulla oblongata 9 Pons 10 Arbor vitae of the cerebellum 11 Cerebellar cortex 12 Dentate nuclei 13 Choroid plexus 14 Inferior cerebellar peduncles 15 Middle cerebellar peduncles 16 Superio cerebellar peduncles 122

26 27 28 29

CN V Flocculus Secondary fissure Posterior notch Central nodule Folds of the vermis (cut through) Uvula – inferior process of the vermis Cerebellar tonsil Vallecular cerebella Posterior median Sulcus of the SC

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Corpus Callosum Median view - midsagittal Superior views - Upper image deep transverse - level of insula - Lower image supf. transverse - level of central sulcus This decussation of fibres is the main form of communication b/n the 2 CH and has 3 parts, other fibres linking parts of the CC are associated with this structure. A = genu or knee B = body or trunk C = splenium or tail A + B + C = corpus callosum = 11

1

Thalamus i = intermediate body /

14 Pituitary i = infundibulum a= anterior / p= posterior

m = medullary striae 2 Optic structures = CN II c = chiasma / n = nerve / r = radiation

15 Cingulum – f = floor of the cingulum suclus

3

CN III

4

IVth ventricle

5

Pons

17 Superior longitudinal fascicles o = occipital part / t = temporal part

6 7

Midbrain Pineal body

18 Short association fibres 19 Central sulcus

8 9

16 Forceps M = major / m = minor

Commissures a = anterior 20 Tapetum p = posterior 21 Floor of Calcaneal sulcus Fornix c = column / X = crus

22 Inferior longitudinal fascicles

10 Septum pellucidum

23 Roof of the inferior horn

11 Corpus callosum L = longitudinal striae / r = rostrum

of the lateral ventricles 24 Insula

12 Interventricular foramen

26 Corona radiata b = base of

13 Lamina terminalis 124

25 Lentiform nucleus

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Diencephalon Thalamus + Epithalamus + Hypothalamus = Diencephalon Superolateral, Mid sagittal The Thalamus (A) is a bilobed oval mass of GM ~ 3cm long - the major sensory relay station - coordinating sensory imput to the CC. The Hypothalamus (C) is the major control of theANS. The Epithalamus (B), which includes the pineal gland (19) has a role in the body clock and awareness of location. These 3 structures develop from the Diencephalon in the embryonic brain. The Thalamus lies immediately inferior to the Corpus Callosum (6) and CC (7) in the 3rd ventricle coordinating information. It has a number of nuclei (1-5) which relate to the CC lobes that are immediately adjacent and feeds information to the Hypothalamus (C) where, via the hypothalamic nuclei, (12-18) information has direct effects on the ANS, pituitary gland actions and the sense of smell. A Thalamus B Epithalamus C Hypothalamus D Pituitary gland = Hypophysis D1 posterior pituitary = neurohypophysis D2 anterior pituitary = adenohypophysis D3 infundibulum = stalk of pituitary

1 Anterior thalamic nuclei 2 Medial thalamic nuclei with Intermediate Mass in b/n 3

Lateral thalamic nuclei

10 Brain stem and cerebral canal b/n the 3rd and 4th ventricles 11 Supraoptic nuclei 12 Arcuate nuclei 13 Ventromedical nuclei

4

Internal medullary laminae 14 Mammillary bodies 5 Geniculate bodies – 15 Dorsomedial nuclei lateral and medial 6 Corpus Callosum

16 Posterior hypothalamic nuclei

7

17 Paraventricular nuclei

Frontal lobe of the CC

8 Optic N = CN II

18 Lateral preoptic nuclei

9 Optic Chaisma

19 Pineal gland

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Fornix = arch Lateral view – in situ Lateral view isolated The Fornix is an arch of fibres carrying signals from the Hippocampus to the mammillary bodies and anterior nuclei of the thalamus and septal nuclei. Beginning in the hippocampus the fimbria converge as the crura of the fornix joining in the midline with fibres crossing from one side of the fornix body to the other via the fornix commissure. Running along the inferior edge of the Septum Pellucidum, the fornix redivides just before the anterior commissure, forming the columns of the fornix.

1 Cingluate gyrus 2 Corpus callosum 3 Suprcallosal gyrus 4 Fornix b = body, c = columns, f = fimbria, l = crura, x = commissure 5 Amygdala & amygdaloid bodies 6 Lateral sulcus 7 Hippocampus f = fimbria 8 Mammillary bodies 9 Nucleus accumbens + septal nuclei 10 Anterior commissure

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THE BRAIN

Language centres cortical centres of verbal expression The frontal lobe contains zones for expressive language, hence motor aphasia results when damaged, difficulty speaking ± writing. The temporo-parieto-occipital regions contain zones for receptive language interpretation, sensory aphasia 2results damage, difficulty understanding hence ± reading. Traditionally areas with are described Broca’s and Wernicke’s both lying in the peri-Sylvian area, around the lateral sulcus, and more highly developed in the dominant CH. This is the LEFT CH (for R handed people). However the 2 functions are not exclusive to these areas. Brodmann areas 22, 41, 42, 44 & 45 are all involved in language production and comprehension. The exact boundaries of these areas vary, and their precise roles are interrelated. B – Broca’s area ~ inferior-frontal gyrus (pars triangularis + pars opercularis) - for speech + writing W – Wernicke’s area ~ superior temporal gyrus + auditory cortex for comprehension and reading

Language processing is a global brain activity and apart form the listed areas other Brodmann areas associated with aspects of language activities are:

4 hand and finger movements, tone and sound formation 7 calculation 18 recognition of objects 19 recognition of colours 21 auditory attention, understanding of sounds with respect to music 22 understanding of sound sequences 37 understanding of numbers 39 recognition of numbers 40 writing 41/42 understanding sequences of sounds + speech 44 formation of phrases and sentences 45 articulation of sentences 46 articulation of names APHASIA – acquired deficiency in language processing incorporating both production and comprehension, due to brain damage. 130

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THE BRAIN

Limbic System Lateral Sagittal Definition – Limbus Gk = limb -It is the 2nd layer of “Brain structures” evolution overlaying the Brainstem – the 1st layer – and underlying the CC and providing substantial interconnectionsb/n them. Allowing for bodily/physiological response to emotional imput and visa versa overriding of the autonomic response by the CC. It contains several interconnected structures, and connects extensively with the Rhinencephalon or “Smelling brain” and the Diencephalon which contains the Thalamic structures.

1 Cerebral Cortex = CC– higher thinking centres 2 Limbic system 3 Brainstem 4 Amygdala – associated with fear and aggression connecting mainly to Rhinencephalon 5 Hippocampus – associated with memory and learning 6 Hypothalamus – associated with body temp regulation and ANS 7 Cingulate gyrus – main connection with the superior CC 8 Corpus Callosum – major decussation joining the R and L CH 9 Anterior thalamic nuclei 10 Olfactory bulb and tract (CNI)

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Midbrain + Hindbrain Anterior view – looking at the front of the midbrain – inferior surface of the brain b/n the forebrain cerebrum and the SC

1 Septum pellucidum 2 Corpus callosum 3 Caudate nucleus 4 Globus pallidus 5 Thalamus 6 Putamen 7 Amygdala 8 Hippocampus 9 SC 10 Medulla oblongata 11 Pons 12 Fornix 13 Crus cerebri 14 Mammillary bodies 15 CC 16 Lateral ventricle

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Septum Pellucidum = Septum lucidum Median view – midsagittal This thin triangular 2 layered vertical membrane of GM and WM separates the lateral ventricles of the brain and the CH. It lies beneath the corpus callosum and attaches to the superior surface of the fornix. Absence of this membrane results in hypothalamic, visual and IQ disorders as well as hypopituitarism.

1 Olfactory b = bulb t = tract 2 Medial root 2+ 3 = olfactory striae 3 Lateral root 4 Paraolfactory area 5 Subcallosal gyrus and sulcus 6 Anterior perforating substance 7 Hippocampal complex 8 Band of Giacomini = tail of the Dentate gyrus 9 Uncus = Parahippocampal gyrus 10 Septum pellucidum 11 Corpus callosum 12 Supracallosal gyrus = Indusium griseum contains the medial and lateral longitudinal fibres (of the corpus callosum) continuous superiorly with cingulate gyrus 13 Fornix b = body / c = columns 14 Fimbriae of the hippocampal complex 15 Dentate gyrus of the hippocampus 16 Amygdaloid bodies 17 Mammilary bodies 18 Hippocampal complex 19 Anterior commissures

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The Thalamus - Part of the Diencephalon Superior view- looking from above Major relay station of the brain – bilobed oval body made up of diverse number of interconnecting nuclei grouped together. Each thalamus is about 3X4X3cm. All sensory imput via THALAMOFUGAL fibres pass into the thalamus before going to the cerebral cortex via THALAMOPETAL fibres, except the olfactory imput; further refinement of cortico–cortical communication is also via the thalamus. Nuclei (ganglia) of GM in the region also communicate extensively with the thalamic nuclei. nuclear group

abbrev. / alt name

1

anteriornucleargp

AN

2 3

ventralanteriorgp ventral lateral gp

VA VL

4

ventralintermediategp

VI

5L

ventral posterio-lateral gp

VPL

5m ventral posterior-medial gp

VPM

6

5 + 4 + accessory semilunar gp VP = ventral posterior gp

7L

lateralgeniculatebody

7m medial geniculatebody

LGB MGB

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pulvinar

9

internal medullary lamina (band ofcontains several nuclei w/in these fibres myelinated fibres)

10

dorsomedialgp

= mediodorsalgp

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lateral posteriorgp

LP

12

medial gp

13

lateral dorsal gp

LD

14

intrathalamicadhesion

central thalamicbody

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intralaminar gp – w/in the lamina

centromedian nuc. CM is the largest

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The Thalamus - Destinations Relations to the CC functional description A1= 1o auditory area / A2 = 2o auditory area / B = Broca’s area E = frontal visual fields / G = gustatory area / M1 = 1o motor cortex / PM = premotor cortex / S1 = 1o sensory cortex / S2 = sensory association / V1association = 10 visualcortex) cortex / V2 = 2o visual cortex / V3 30 visual cortexarea (visual nuclear group

destination of.. / output

1

anterior nuclear gp

cingulate gyrus - emotion, limbic system

2

ventral anterior gp

motor cortex initiate actions, resting muscle tone + insula cortex, globus pallidus

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ventral lateral gp

motor + premotor cortex motor activity coordination

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ventral intermediate gp

cerebral cortex areas 4,6 from cerebellum motor activity coordination

5L

ventral posterio-lateral gp

somatosensory cortex somatic sensation of body pain and temp

5m ventral posterior-medial gp

somatosensory cortex (post central gyrus areas 3,1,2) somatic sensation of face and jaw – pain and temp + taste.

6

5 + 4 + accessory semilunar+ gustatory cortex taste. gp= ventral posterior gp

7L

lateral geniculate body

visual cortex vision

7m medial geniculate body

auditory cortex hearing

8

pulvinar

posterior association cortex sensory information integration partic audition & vision

9

internal medullary lamina concerned with emotional arousal and control diffuse (band of myelinated fibres) cortical projection

10

dorsomedial gp

prefrontal cortex* - executive function, social skills affection, memory

11

lateral posterior gp

parietal lobe,cingulate gyri,- sensory information integration

12

medial gp

hypothalamus , frontal cortex ANS integration

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lateral dorsal gp intrathalamic adhesion

cingulate gyrus - emotional expression communicates with other thalamus

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intralaminar gp – w/in the lamina

frontal cortex + basal nuclei - arousal largest – motor control

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Ventricles Lateral view – looking in at the side of the brain Coronal view schema – looking at the front of the ventricles The brain and SC sit in a closed cavity the Skull and Vertebral cavity surrounded by CSF – a filtered form of blood plasma from the BBB which connects with 4 internal cavities and the spinal canal. The 4 cavities or VENTRICLES produce the CSF which circulates around the brain and SC, cushioning and nourishing the neuraltissue. 3 ventricles lie in the cerebrum and the 4th is in the brainstem continuous with the SC inferiorly and the subarachnoid space via 3 openings in the roof of the 4th ventricle, 2 lateral and 1 posterior.

1 frontal lobe 2a anterior horn of the lateral ventricle(s) 2b body of the lateral ventricle(s) 2i inferior horn of the lateral ventricle(s) 2p posterior horn of the lateral ventricle(s) 3 3rd ventricle 4 4th ventricle 5 cerebral aqueduct 6 lateral recess(es) – foramen of Luschka 7 median aperture and foramen of Magendie 8 SC 9 hindbrain 10 brainstem / pons 11 interventricular foramen 12 parietal lobe 13 occipital lobe 14 cerebellum 15 spinal canal See website for more details on the Ventricles Superior view 142

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Ventricles – relations Superior view - looking down from above The ventricles have intimate relations with the Choroid plexus and its parts: Tela Choroidea and Glomus Choroideum. CSF produced by these tissues flows through the ventricles, the spinal canaland out around and spinal cord. Anythey blockage results in swelling crushingthe of brain the tissues nearby, hence are most vulnerable to and cerebral oedema.

Relations

1 2 3 4

Corpus callosum g = genu / s = splenium Caudate nucleus h = head / b = body / t = tail Septum pellucidum c = cavity Fornix h = hippocampus

5 Amygdaloid body 6 Optic radiation 7 Tapetum Ventricle components 10 Lateral ventricle 10a anterior horn of the lateral ventricle(s) 10b body of the lateral ventricle(s) 10i 10p 11 12 13 14c 14g

inferior horn of the lateral ventricle(s) posterior horn of the lateral ventricle(s) 3rd ventricle suprapineal recess cerebral aqueduct choroid plexus glomus choroideum

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4th ventricle lateral recess(es) – foramen of Luschka median aperture and foramen of Magendie posterior recess spinal canal

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Ventricles – relations Ventricles opened for internal view The ventricles are spaces and this view emphasizes this fact. The top view is pf one of the lateral ventricles and the lower view of the transposed 3rd and 4th ventricles which sit higher in b/n the large lateral ventricles Ventricles make up 3-4% of the weight of the brain.

Ventricle components

11 suprapineal recess

1

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Lateral ventricle

1a anterior horn of the lateral ventricle(s)

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1b body of the lateral ventricle(s)

15c inferior vermis

1i

inferior horn of the lateral ventricle(s)

1p posterior horn of the lateral ventricle(s) 2

interventricular foramenjoining the laterals with

14 cerebral aqueduct 16 median foramen of posterior recess 17 posterior recess = median recess 18 ependymal pocket – lower ends of the 4th ventricle

3

the 3rd ventricle 3rd ventricle

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4th ventricle

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roof of the 4th ventricle

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triangular recess

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anterior commissure

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optic chiasma infundibular recess

floor of the 4th ventricle

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CRANIAL NERVES

The Cranial Nerves CN are defined as Ns which leave from the skull (cranium) rather than the SC. There are 12 pairs, and they are numbered in the order they leave the skull not necessarily the same order that they leave the brain. Their names are an attempt to reflect their function. Below is a summary of the Cranial Nerves and their functions. They are listed in the order they leave the Cranium/Skull.

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The Cranial Nerves – summary 5 are purely motor III, IV, VI, XI, XII; 3 purely sensory I, II, VIII and the rest 4 are mixed. All exit from the ventral surface of the Brainstem and related structures except 3 CNs - CN 1 and II which act as extension of brain tissue rostral to the brainstem and CN IV which exits from the dorsal brainstem surface and crosses to the contralateral side immediately. All CNs cross partially to the contralateral side hence most structures have dual innervation so that UMN lesions (eg. stroke) do not usually result in complete loss of function, whereas LMN lesions (eg. trauma) generally do so. Nucleus Solitarius is SENSORY the site of neuron srcin for CNs VII, IX & X. Nucleus Ambiguus is MOTOR the site of neuron srcin for CNs IX & X

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CRANIAL NERVES

CN I Inferior view – looking up from below to the base of the brain Superior view – looking down into the ACF – cranial exit Magnified Sagittal view through Olfactory bulb The Olfactory N-pure special sensory SMELL- functions as a brain extension

Origin the olfactory bulb (1) Course rootlets from receptor cells in the nasal lining (6) near the superior concha pass up through the Cribiform plate of the Ethmoid bone (5) synapse in the bulb (1) and sensory information then moves to the main brain tissue via the olfactory tracts (2) projecting to the olfactory areas of the CC, see Rhiencephalon. Cranial Exit cribiform plate Branches none Lesions Aetiology

amnosia inability to smell (and often taste is affected) injury to the ACF

1 Olfactory bulb 2 Olfactory tract 3 Mitral cell 4 Fibrous processes of receptor cells 3,4 = Glomerulus of fibres b/n the receptor cells and the Mitral cells to transmit and amplify the sensory material 5 Ethmoid bone with “olfactory holes” – in the Cribiform plate to allow passage of olfactory receptor N cell axons 6 Mucosa and CT for BVs and support to the Ns 7 Receptor cells 8 Basal cells of the nasal epithelium 9 Columnar epithelial cells 8,9 = nasal epithelium = pseudocolumnar epithelium present in most of the respiratory system 10 Glycocalyx on apical surface of the epithelial cells –sticky 11 Mucous secreted from the nasal glands 12 Nasal glands 13 Long microvilli and knob – specialized endings of the receptor cells 152

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CN III Schema of Oculomotor nuclei and their CNS and ANS connections Most of the muscles of the eye are supplied by CN III which has connection with the ANS via the parasympathetic fibres fromthe Accessory nucleus responsible for the light reflex.

1

pretectal nucleus

2

superior colliculus

3f fibres of CN III - a combination of the motor fibres from the main nucleus and the PNS motor fibres from the accessory nucleus 3m main oculomotor motor nucleus 3mf fibres from the motor nucleus 3p accessory oculomotor nucleus = Edinger-Westphal nucleus 3pf PNS fibres 4

tectobulbar fibres

5

medial longitudinal fasciculus

6

red nucleus

7 8

substantia nigra central canal

9

cerebral cortex – motor

Exit of the CN III from the base of the skull

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CN IV Schema of Trochlear nuclei and their CNS connections Only the Superior Oblique muscle in the eye is supplied by the Trochlear N -= so called because of its external association with the trochlea or pulley in the eye socket (see the A to Z of the Head and Neck for further details). It is the only CN to exitinthe the dorsal surface, after complete decussation theBrainstem superior from medullary velum. It courses around to the anterior surface, through the cavernous sinus and leaves via the optic canal as do the other eye related CNs.

1 mesencephalic nucleus of CN V 2 superior colliculus 2f fibres form the superior colliculus - tectobulbar fibres 3 inferior colliculus 4f trochlear N fibres 4n trochlear N nucleus 5 medial longitudinal fasciculus 6 crus cerebri 7 substantia nigra 8 central canal 9 cerebral cortex – motor Pathway of the CN IV from the brainstem dorsal surface and exit from skull

10 midbrain 11 superior cerebellar peduncle 12 cavity of 4th ventricle 13 MO 14 superior medullary velum 15 pons

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CN V The Trigeminal N – mixed : sensory, special sensory, somatic motor fibres, and parasympathetic fibres,which relate to the muscles and skin of the face. Origin Sensory : NR terminates in the sensory nuclei extending from the Pons to C2 Nu – the rootlets enter from midlateral surface of the Pons Motor : NR from masticator motor nucleus in the Pons

Course The Trigeminal N has 3 large branches. Ophthalmic (V1 sensory), Maxillary (V2, sensory) and Mandibular (V3, motor and sensory). The sensory branches join the trigeminal ganglion in the MCF Cranial Exits: foramen ovale, superior and inferiororbital fissures.

BRANCHES in detail The Mandibular N = V3 motor root + mandibular branch of the sensory root of the Trigeminal N and has 6 branches. The Mandibular N innervates the muscles of mastication: Mylohyoid and the anterior belly of Digastric; Tensor Veli Palatini and Tensor Tympani. The sensory part of the Mandibular N carries general sensory information from the mucous membranes of the mouth, cheek, anterior 2/3 of the tongue, the lower teeth, skin of the lower jaw, side of the head and the meninges of the anterior and middle cranial fossae. The 2 other sensory branches of CN V also converge on the trigeminal ganglion via the cavernous sinus. The Ophthalmic N has 7 branches and enters the cranium through the superior orbital fissure from the orbit and the skin of the forehead and head. The Maxillary N has 8 branches and enters the cranium through the inferior orbital fissure, and the pterygopalatine canal via the Pterygopalatine fossa and Foramen Rotundum, carrying information from the face, cheek and upper teeth and soft andhard palate, nasal cavity and pharynx. Meningeal sensory branches enter the trigeminal ganglion w/n the cranium.

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CN V Cont Ophthalmic N branches V1

1 Infratrochlear 2 Anterior Ethmoid 3 Posterior Ethmoid 4 Lacrimal 5 Supraorbital 6 Supratrochlear 7 Nasociliary Maxillary N branches V2

1 Zygomaticotemporal 2 Zygomaticofacial 3 Post. Superior Alveolar 4 Nasopalantine 5 Greater Palatine 6 Lesser Palatine 7 Middle & Anterior Alveolar branches 8 Infraorbital

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Palatine branches from V2 in greater detail 1 incisive fossa 2 nasopalatine N 3 greater palatine N 4 Lesser palatine N 5 Posterior nasal spine 6 palatine bone -horizontal plate 7 hard palate (Maxilla)

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Mandibular N branches V3 1 Auriculotemporal 2 Lingual 3 Inferior Alveolar 4 N to Mylohyoid 5 Mental 6 Buccal for innervation to the face see the Dermatomes

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CN V Schema of Trigeminal nuclei and their CNS and ANS connections coronal section through the brainstem transverse section through the mid pons Most of the sensory supply to the face and the motor supply to the muscles of mastication come from theTrigeminal N. Hence it travels with the CNs supplying the eye and has ANS imput. It has an extensive SC extension of its main sensory nucleus present until C2.

1 CC 2 mesencephalic nucleus 3 motor nucleus 4 main sensory nucleus – continuous with 5s 5g Trigeminal ganglion 5i Ophthalmic N = CN V1 5ii Maxillary N = CN V 2 5iii Mandibular N = CN V3 5l Trigeminal leminiscus 5n Trigeminal N 5s spinal nucleus of the Trigeminal N 6 thalamus 7 midbrain 8 proprioceptive fibres from the face and eye synapse in 2 9 substantia gelatinosa 10 C2 11 MO

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CRANIAL NERVES

Neural pathways for CN V = Trigeminal N and interrelationships with CN III,VII & IX (Oculomotor, Facial & Glossopharyngeal) This schema demonstrates their interactions and the sites where they occur. The name of the N may change at points along its pathway e.g. Nervus intermedius (1) and Chorda tympani (2)

A B C D E F 1

Intracerebral from the Bs to C2 Intracranial Emergence from the skull Branches & N pathways Ganglia Ns & end organs Nervus Intermedius

2 Tympani N fissure 1!Chorda 2 via petrotympanic 3 submandibular + sublingual ganglia 4 N to sublingual gland 5 N to submandibular gland 6 N supplying taste for the ant. 2/3 of the tongue + 7 Lingual N (CN V3) 8 pterygopalatine ganglion 9 N to mucous glands 10 Zygomatic N 11 Lacrimal gland 12 greater petrosal N 12!13 via foramen lacerum 13 N of Pterygoid canal 14 N to Mucous glands 15 ciliary ganglion 16 short ciliary Ns 17 eye 18 Nasociliary N branch of V1 19 Lacrimal N branch of V1 168

20 Frontal N branch of V1 21 Auriculotemporal N 22 lesser petrosal N 23 otic ganglion 24 N to Parotid gland 25 N to Labial gland 26 Mental N (to the chin) 27 (to Inf.the alveolar chin &N jaw) 28 Ns to Tensor Typmani & Tensor Veli Palatini CN IIIa fibres from the Accessory nucleus (ParS) CN V Trigeminal N CN Vg Trigeminal ganglion CN Vm motor nucleus CN Vs sensory nucleus CN VII Facial N CN VIIa superior salivary nucleus CN IXa inf. salivary nucleus CN VIIl lacrimopalatonasal ganglion CN IX Glossopharyngeal N exit jugular foramen V1 Ophthalmic N - pure sensory exit foramen rotundum V2 Maxillary N - pure sensory exit foramen lacerum V3 Mandibular N - motor + sensory exit foramen ovale © A. L. Neill


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Facial Dermatomes The Face is innervated by the Trigeminal N = CN V and its branches. The top of the head and neck by the upper cervical spinal Ns

1 Supra-orbital N (V1) 2 Supratrochlear N (V1) 3 Lacrimal N (V1) 4 Infratrochlear N (V1) 5 External nasal N(V1) 6 Zygomaticofacial N (V2) 7 Infra-orbital N (V2) 8 Mental N(V3) 9 Buccal N (V3) 10 Great Auricular N (C2,3) 11 Anterior cutaneous N of the Neck (C2-3) 12 dorsal branches of C6 13 dorsal branches of C5 14 dorsal branches of C4 15 dorsal branches of C3 16 Auriculotemporal N (V2) 17 Lesser Occipital N (C1,2) 18 Greater Occipital N (C2) 19 Zygomaticotemporal N (V2) note if the “Onion skin” pattern shown in the lower image is present this indicates a lesion compressing the Bs and so the nuclei of CN V.

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CN VI Schema of Abducens N nuclei and their CNS connections Pathway of the CN VI from the brainstem and exit from skull The Abducens N – pure motor, supplies the Lateral Rectus Origin

ventral surface of the Pons

Courses

ventrally/anteriorly exits the DM lateral to Dorsum Sellae enters the cavernous sinus lateral to the carotid artery

Cranial Exit superior orbital fissure

1 cerebral cortex 2 superior colliculus 2f fibres form the superior colliculus - tectobulbar fibres 3 pons 4 cavity of 4th ventricle 5 medial longitudinal fasciculus 6f fibres of Abducent N 6 abducent motor nucleus 7 MO

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CRANIAL NERVES

CN VII Diagram of the pathway from CC primary motor cortex (UMN) !CN VII motor nucleus(LMN) ! through facial canal (longest intracranial pathway of any CN) ! exit. The Facial N – mixed : sensory, special sensory, somatic motor fibres, & Para Ns Origin ventral surface of the Brainstem – Pontomedullary junction Course

enters the IAM, travels with CN VIII – branch Greater Petrosal N (Para Ns) facial canal (petrosal canal) – branch Chorda Tympani (Para Ns + SSNs)

Cranial Exit stylomastoid foramen Longest intracranial pathway of any CN

1 cortical input to facial motor nucleus – corticobulbar tract 2 motor nucleus of the Facial N 3 motor branches of the Facial N 4 IAM 5 stylomastoid foramen

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CRANIAL NERVES

Facial – CN VII cont Main Motor branches of the Facial Nerve - lateral view of the skull The main motor fibres of the Facial N supply the muscles of facial expression, via 5 branches and travel in the superficial fascia of the face.

1 2 3 4 5

Temporal N to Auricularis, & Epicranius Zygomatic N to Zygomaticus muscles & muscles around the eye Buccal N to muscles of the cheek & upper lip Mandibular N to muscles of the lower jaw (eg N to Mylohyoid-7) Cervical N to Platysma

Other branches of the Facial N The Greater Petrosal N leaves the IAM, on the ant. surface of the petrous part of the Temporal bone, in the MCF. It passes forward across the foramen lacerum and joins the Deep Petrosal N (sym. fibres from the superior cervical ganglion). These 2 Ns enter the pterygoid canal as the Nerve of the Pterygoid canal. The N of the Pterygoid canal exits the canal - synapses in the Pterygopalatine ganglion in the Pterygopalatine fossa. It supplies branches to the lacrimal gland and the mucous secreting glands of the nasal & oral cavities. The Chorda Tympani (6) joins the Lingual N (9) from CN V3 in the infratemporal fossa prior to synapsing in the submandibular ganglion in the lateral floor of the oral cavity. Fibres from this ganglion innervate the submandibular & sublingual glands, – not the parotidgland. via the inferior Alveolar branches (8). The Para Ns of Chorda Tympani exit thebrainstem via NervusIntermedius, which lies b/n CNVIII and the somatic motor fibres of the Facial(VII). N The fibres of taste (SpecialSensory) of theanterior 2/3 of thetongue, and the general sensory fibrestravel with the Chorda yTmpani also via Nervus Intermedius and enter theskull through thepetrotympanic fissure.

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Chorda Tympani N to Mylohyoid Inferior Alveolar N Lingual N © A. L. Neill


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CRANIAL NERVES

Lesions of the Facial N The motor nucleus of CN VII is in the caudal portion of the ventrolateral pontine tegmentum. Axons from the LMN travel dorsally, loop around the CN VI nucleus (motor) & exit the ventralpons medial to the CN V spinal nucleus. Along with the motor fibres of CN VII are the ParaNs & the sensory components which branch off and form the Nervus Intermedius. LMNs from the dorsal CN VII motor nucleus receive bilateral UMN input (from both sides of the CC) and innervate the muscles of the upper face. LMNs from the ventral CN VII motor nucleus receivecontralateral UMN inputs and innervate the lower muscles of the face Hence both sides of the brain control the muscles of the upper face, while only the contralateral side of the brain controls the muscles of the lower side of the face. Hence lesions in the corticobulbar tract, UMN lesions, result in central facial palsy = central seven, spastic paralysis on the contralateral lower face, while LMN lesions result in paralysis of the lower muscles on the ipsilateral side = Bells Palsy. In both cases there may be difficulty in sucking, swallowing, and talking. In both cases the forehead muscles tend to be spared, and as the upper larynx and pharynx are also innervated by CN V and CN XI motor nuclei, these areas have multiple innervation, there is great potential for rehabilitation of this area eg swallowing after CVAs / strokes.

Image of facial palsies Bells’ / Central seven Bell’s on the ipsilateral side LMN Central facial Palsy on the contralateral side UMN 1 drooping eyelid ± dry eye ± excessive tears 2 facial paralysis/weakness ± twitching 3 drooping mouth ± dry mouth ± impaired taste – cannot blow / whistle /close lips firmly 4 forehead muscles generally spared 5 difficulties in swallowing, talking

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CRANIAL NERVES

Neural pathways for CN VII = Facial N and interrelationships with CN V, IX & X (Facial, Glossopharyngeal & Vagus). CN VII travels with both CN V & CN IX to reach ti s destination. It also interacts with the Vagus N (CN X) and has a second component, the Chorda Tympani. This schema demonstrates these interactions and the sites where they occur. CN VII travels intracranially extensively throughthe Petrosal canal (facial canal). At the endorgans often the motor branches are from CN VII & the sensory from CN V.

A B C D 1 2 3 4 5 6 7 8 9

Intracerebral Intracranial Intrapetrosal path = facial canal (also intracranial) Extrapetrosal ganglia, pathways, Ns & endorgans greater petrosal N pterygopalatine ganglion auriculotemporal N (sensory branch to EAM) infraorbital N buccal N mental N inferior alveolar N Ns to Stylohyoid & Digastric post. belly chorda tympani + motor facial N

9c chorda tympani branching just before cranial exit – part of taste sensation, supplies ant. 2/3 of the taste & pain of the tongue - inhibits other sensory input 10 lingual N (from CN V3) 11 submandibular + sublingual ganglia 12 auricular br. of CN X 13 N to Stapedius 14 Geniculate ganglion CN VIIm Facial N motor nucleus CN VIIa CN IXg CN VIIl CN IX CN X CP 180

superior salivary nucleus of the Facial N gustatory nucleus of the Glossopharyngeal N lacrimopalatonasal ganglion of the Facial N Glossopharyngeal N exit jugular foramen Vagus N Ns from the cervical plexus – proprioceptive © A. L. Neill


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CRANIAL NERVES

CN VIII in the ear Coronal section of the ear exit and relationship with CN VII Auditory N = Vestibulocochlear N

1 cochlea 2 eustachian tube = auditory tube 3 round window 4 stapes 5 incus 6 malleus 7 CN VII = Facial N 8c Cochlear N – part of CN VIII 8v Vestibular N part of CN VIII 9 Tympanic membrane 10 IAM 11 EAM 12 Pinna

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CRANIAL NERVES

Auditory N = Vestibulocochlear N – CN VIII Diagram of the intracranial pathway and entrance of the CN VIII coronal section of the skull. The Vestibulocochlear N – pure special sensory with 2 parts = vestibular + audition = BALANCE & HEARING Origin

sensory cells attached to specialized organs in the membranous labyrinth (AKA boney labyrinth) in the petrous part of the Temporal bone Cochlear duct – connected to the boney ossicles for sound transmission Vestibular apparatus – fluid filled tubes to detect changes in body movement

Course

cells travel to and then through the internal auditory meatus with CN VII and Nervus intermedius enteringthe brain at the pontomedullary junction lateral to VII in the cochlear nucleus and the vestibular nuclear complex.

Cranial Exit remains in the cranium in the internal auditory meatus

1 crus cerebri 2 red nucleus 3 3rd Ventricle 4 vertebral artery 5 sigmoid sinus 6 MO 7 CN VII & Nervus intermedius exiting with … 8 CN VIII 9 CN IX exit 10 CN X exiting with .. 11 CN XI 11s Spinal root of CN XI 12 SC

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CRANIAL NERVES

CN IX The Glossopharyngeal N – mixed : sensory, special sensory, somatic motor fibres, and parasympathetic fibres, which relate to the tongue and pharynx. Origin Course

ventral surface of the Brainstem –a series of rootlets b/n olive and inferior cerebellar peduncle branch intracranial – the Tympanic N (Para Ns + sensory fibres) exits via Foramen Ovale as the Lesser Petrosal N supplies parotid gland

Cranial Exitjugular foramen travels and exits with CN X. Motor fibres supply the Stylopharyngeus muscle. General sensory fibres synapse in the superior glossopharyngeal ganglia, go to the Bs and terminate in theTrigeminal nucleus. These fibres supply the skin of the external ear, the inner surface of the tympanic membrane, posterior one-third of the tongue and the upper pharynx. Sensory nerve fibers for the autonomic system - srcinate from the carotid body (oxygen tension measurement) and carotid sinus (blood pressure changes) and Special sensory fibres - detect taste from the posterior 1/3 of the tongue - converge and synapse in the inferior glossopharngeal ganglion, then enter the Bs and terminate inthe upper part of the Nucleus Solitarius. (also known as the Gustatory nucleus).

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CRANIAL NERVES

Vagus – CN X - “wandering nerve” The Vagus N – mixed : sensory, somatic motor fibres, & parasympathetic fibres. ParaNs have input to the CVS, respiratory system from the larynx to the bronchioles & the GIT to the splenic flexure (23). Origin

Motor : Nucleus Ambiguus,Dorsal Motor nucleus of the Vagus (ParaNs) Sensory : terminate in the superior (10s) and inferior (also containing ParaNs) vagal ganglia (10g).

Course

rootlets exit via the MO, the motor division forming 3 major branches

Cranial Exit jugular foramen (22) The Vagus N is the longest CN. The motor fibres travel with CN XI (11). The sensory fibres travel with CN IX (9). Test:

Gag reflex

3 MOTOR BRANCHES in detail 1 the Pharyngeal N, (10p) travels b/n the int. (2) & ext. (3) carotid arteries - enters the pharynx at the upper border of the middle constrictor muscle and supplies the all the muscles of the pharynx and soft palate (except the Stylopharyngeus & Tensor Veli Palatini). 2 the Superior Laryngeal N branches distal to the pharyngeal branch descends lateral to the pharynx. It divides into an int. (sensory & autonomic) (10i) and ext. branch (10e). The ext. branch innervates the Cricothyroid muscle. 3 the Recurrent Laryngeal N is different on the R and L sides. R leaves the Vagus anterior to the subclavian, loops around the artery and ascends b/n the trachea and the oesophagus (19). L leaves the Vagus anterior to the aortic arch andloops around it to ascend through the superior mediastinum. Hence the L Recurrent Nis sensitive to changes in the diameter of the aortic arch as in an aneurysm. It ascends b/n the oesophagus (18) & trachea. Both Ns enter supply intrinsic muscles of larynx. The Para Ns of the Vagus N synapse in ganglia close to their target organs, and forma networks or plexi around these organs. Feedback comes from receptors in these organs. Sensation from the mucous membranes of the epiglottis, base of the tongue, aryepiglottic folds and the upper larynx travel via the Internal Laryngeal N. Sensation below the vocal folds of the larynx is carried by the Recurrent Laryngeal Ns. 188

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10s 22 10g 11 20 21

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CRANIAL NERVES

Vagus – CN X - “wandering nerve” cont pathway of the wandering nerve in the neck, thorax and abdomen 1 EAM 2 internal carotid artery

3 4 5 6 7 8 9

external carotid artery common carotid artery pulmonary trunk (venous) inf. Phrenic artery L lobe of the liver Trapezius CN IX = Glossopharyngeal N

10 X = vagus 10aCN anterior vagalNtrunk 10e external vagal N 10g vagal ganglia 10i internal laryngeal N 10p Pharyngeal N branch of CN X to pharyngeal plexus 10s superior vagal ganglion 11 CN XI = Accessory N 12 13 14 15 16 17 18

CN XII = Hypoglossal N oesophageal plexus upper R pulmonary vein R pulmonary artery R main bronchus deep oesophageal plexus + cardiac plexus oesophagus

19 20 21 22 23

R recurrent laryngeal N - looping around the subclavian artery jugular vein phrenic N (C3,4,5) jugular foramen gastric plexus

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CRANIAL NERVES

Vagal innervation of the Larynx Sagittal view of the Larynx showing CN X laryngeal branches Note the differences in R and L recurrent laryngeal Ns. Clinically this is significant as an enlarged Aortic arch may present as a dry hacking cough.

1 Vagus N (CN X) 1A Superior Laryngeal N 1B Recurrent Laryngeal N (L) – note the R branch curls around the Aortic arch - removed 1C cardiac branches of Vagus 2 Thyroarytenoid muscle 3 Lateral Cricoarytenoid 4 Posterior Cricoarytenoid 5 Epiglottis 6 Thyroid cartilage 7 Cricoid cartilage 8 Aryenoid cartilages 9 Oesophagus (removed posteroir to Trachea)

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Overview - Vagus & the ANS 1 2 3 4 5

ciliary ganglion sympathetic chain CN III MO Solar plexus

8 vesical plexus 9 splanchnic Ns 10 CN X cranial Parasympathetic outflow 10p parasympathetic plexi located

6 sacral outflowParasympathetic 7 SC

near target organs with CN X

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10p

10p

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PUPIL SIZE SALIVARY SECRETIONS 2

HEART RATE

BRONCHIAL SIZE 5

GASTRIC MOVEMENT PANCREATIC & BILE SECRETIONS 9

ADRENAL SECRETIONS 8

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BLADDER CONTRACTION LIBIDO 195

CRANIAL NERVES

Vagus – CN X autonomic input to the heart + BP

1 hypothalamic autonomic centre 2 sensory input from … 3+5+6 3 carotid sinus 4 aortic sinus 5 arterial baroreceptors 6 sinoatrial node 7 arteries 8 sympathetic motor fibres "tone of arteries 9 sympathetic outflow 10 CN X = Vagus N 10n Bs containing solitary tract and nucleus 10p

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ganglion of the Cardiac plexus

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10 10p

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CRANIAL NERVES

Vagus – CN X Input to the tongue, oesophagus and upper GIT

1 input from the CC 2 pons 3 solitary tract and nucleus 4 nucleus ambiguous 5 dorsal vagal nucleus 6 SC 7g phrenic N nucleus 7n phrenic N 8 diaphragm 9 stomach 10n CN X = Vagus N 10p oesophageal plexus 11 physiological sphincter of oesophagus smooth muscle 12 crura of diaphragm – skeletal muscle 13 oesophagus 14 tongue 15 pharynx

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CRANIAL NERVES

Accesssory – CN XI lateral view of the Bs superior view of the base of the skull CN XI crossing in the neck and supplying the 2 muscles The Accessory N – pure motor supplies cervical parts of Trapezius (1) + Sternocleidomastiod (2) Origin ventral surface of the MO + cervical SC Course

ascends rostrally through the Foramen Magnum joining and traveling with the Vagus N (CN X)

Cranial Exit jugular foramen

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CRANIAL NERVES

Neural pathways for CN IX, X & XI = Glossopharyngeal, Vagus & Accessory Ns and their interrelationships CN IX, X and XI travel together and share innervation at for least part of their pathways. This schema demonstrates their interactions and the sites where they occur.

A Intracerebral B Intracranial C Jugular Foramen + VC exits for cervical Ns D Peripheral distribution 1 otic ganglion 2 to the parotid gland 3 to the tympanic membrane / Tympanic N 4 Pharyngeal plexus 5 Laryngeal plexus 6 Coeliac plexus = Solar Plexus ie part of the abdominal plexi 7 Cardiac and Bronchi plexi 8 Ns to Sternocleidomastoid 9 Ns to Trapezius CN VIIb

inferior salivatory nucleus

CN VII, IX, Xs Nucleus Solitarius -sensory with imput from the indicated CNs CN IX X m

Nucleus Ambiguus -motor Ns from CN IX & X

CN Xs

dorsal Sensory nucleus of the Vagus N

CN Xm CN XI sc

dorsal Motor nucleus of the Vagus N spinal nucleus of the Accessory N (motor)

C1, C2, C3

cervical spinal Ns

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m X IX N C

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,X , X I I,I V N C

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SPECIAL SENSES

Nuclei for CN IX, X & XI = Glossopharyngeal, Vagus & Accessory Ns & their interrelationships CN IX, X and XI are intimately related they emerge from the skull together, travel together and share innervation at for least partof their pathways.This diagram lists their main nuclei ofthese Cranial Nerves and the interrelationships with the other CN nuclei.In some casesthe same nuclei haveseveral names,if significant each one has been listed with their equivalents.

3 3a 4 5m

Oculomotor nucleus Autonomic accessory nucleus of CN III Trochlear nucleus motor nucleus of Trigeminal N - part of the Spinal nuclear complex of the Trigeminal N 5ma motor nucleus of Trigeminal N = Masticatory nucleus 5me Mesencephalic nucleus of Trigeminal N 5s 6 7i 7l

Spinal nucleus of the Trigeminal N Abducens nucleus Inferior salivatory nucleus Lacrimopalatonasal nucleus = autonomic nucleus of the Facial N 7m Motor nucleus of the Facial N 7s Superior salivatory nucleus 8b Superior vestibular nucleus = nucleus of Betcherew 8c dorsal & ventral Cochlear nuclei 8d 8i 8l 8s 9a 9g

Lateral vestibular nucleus = Deiters nucleus inferior vestibular nucleus Superior vestibular nucleus = Lewardanowsky nucleus Medial vestibular nucleus = Schwalbe nucleus Nucleus ambiguus upper part - leads to CN IX fibres Gustatory nucleus - upper part of the Nucleus Solitarius = Solitary tract 9s Nucleus of the solitary tract with CN IX fibres 10a Nucleus ambiguus middle part -leads to CN X fibres 10m Dorsal motor nucleus of the Vagus N 10s Nucleus of the solitary tract with CN IX fibres 11a Nucleus ambiguus lower part -leads to CN XI fibres = Laryngeal nucleus 11s Spinal nucleus of the Accessory N 12 Hypoglossal nucleus 204

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Hypoglossal – CN XII lateral view of the Bs superior view of the base of the skull The Hypoglossal N – pure motor –supplying tongue muscles (except Palatoglossus) Origin

hypoglossal nucleus –ventrolateral sulcus of Medulla Oblingata running with fibres from C1-3 in the Ansa Cervicalis

Course

passes b/n internal carotid artery and jugular vein loops above the Hyoid bone and runs on the edge of the Hypoglossus muscle. joining the Vagus N (CN X)

Cranial Exit hypoglossal canal

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SPECIAL SENSES

Neural pathway for CN XII = Hypoglossal N & the relationship with the upper Cervical SNs CN XII hypoglossal = under the tongue interacts with CN IX and V in supplying the muscles of the tongue and with the upper Spinal Nerves in the throat – hyoid and thyroid muscles. This schema demonstrates their interactions and the sites where they occur.

A Intracerebral for CN XII & SC for C1-3 B Intracranial for CN XII & Vertebral canal for C1-3 C Hypoglossal canal for CN XII & Intervertebral foraminae for the SNs D Peripheral distribution 1 N to Styloglossus 2 Ns to Muscles of the Tongue 3 Lingual N = from CN V3 4 N to Geniohyoid Muscle 5 N to Thyrohyoid muscle 6 Ansa Cervicalis 7 Ns to Infrahyoid muscles CN XIIn

Nucleus of CN XII – motor

C1m

motor nuclei of the C1 -ventral horn

C2-3s

sensory nuclei of C2, C3 – dorsal horns

C1, C2, C3 cervical spinal Ns

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Optic - CN II Sagittal view showing CN II pathway Transverse view - looking down from above The Optic N - pure special sensory VISION - functions as a brain extension Origin

the retinal bipolar cells synapsing on specialized light receptors – rods & cones (1)

Course cells coalesce at the back of the eye as the Optic N (2) – moves down the Optic canal, 50% cross at the Optic chiasma (3), and proceed as the Optic tract on the contralateral side (4) to the Lateral Geniculate body (5). A further synapse here forms the Optic radiation (6) which travels to the Visual cortex – Brodmann areas 17,18, 19. Cranial Exit orbital fissure /optic canal

Branches none Lesions

blindness

Aetiology injury to the eyeball &/or retina

1 Retina 2 Optic N 3 Optic chiasma 4 Optic Tract 5 Lateral Geniculate body 6 Optic radiation 7 Visual Cortex 1o and 2o in b/n pareito-occipital & calcarine sulci 8 Corona Radiata 9 Brainstem 10 Superior colliculus 11 Pulvinar (Thalamus) 12 Medical geniculate body 13 Mammillary body 210

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Blood Vessels of the Eye Horizontal

1 Central vessels of the retina a= artery v=vein 2 ophthalmic artery 3 internal carotid artery 4 cerebral arteries a=anterior /m= middle / p= posterior branches 5 lateral striate artery 6 optic radiation 7 visceral cortex 8 lateral geniculate body 9 optic tract 10 basilar artery 11 anterior choroidal artery 12 communicating artery a=anterior / p= posterior 13 superior hypophysial artery 14 retina 15 choroid 16 sclera 17 short posterior ciliary arteries 18 DM 19 AM 20 PM 21 subarachnoid space 22 plial plexus 23 central collateral artery 24 circle of Zinn 25 lamina cribosa

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SPECIAL SENSES

Visual field defects Lesions complete or partial along the visual pathway result in different visual field defects. This diagram represents the views seen in the R and L eyes when these lesions occur. L column represents the view from the L eye R column represents the view from the R eye

1 Pressure on the L Optic N causes circumferential blindness on L side - the ipsilateral side 2 Total blindness on the affected side of the cut CN II 3 Pressure on the L optic tract results in R sided nasal hemianopia 4 Pressure / Lesions on the Optic chiasma (as in pituitary tumors) result in bilateral Temporal hemianopia – no side vision 5, L temporal hemianopia + R nasal hemianopia is the 6, result from lesions in the optic tract (5), Optic radiation 7 (6,9) and or in the Visual cortex (7,8) 8 visual cortex 9 Optic radiation 10 lateral geniculate body 11 Optic chiasma 12 Optic N = CN II 13 nasal bridge

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SPECIAL SENSES

CN III, IV, V, VI srcins lateral view of the ACF with lateral wall of the cavernous sinus removed - showing commencement neural pathways of CN II, III IV V and VI

1

ACF

2c Optic Chiasma 2n CN II = Optic N 3g ciliary ganglion 3n CN III = Oculomotor N 4n CN IV = Trochlear N 5g Trigeminal ganglion 5i Ophthalmic N = CN V1 5ii Maxillary N = CN V 2 5iii Mandibular N = CN V3 5n Trigeminal N 6

Abducens N = CN VI

6m lateral rectus (muscle of CN VI) 7a anterior cerebral artery 7p posterior cerebral artery 8 superior cerebellar artery 9

pterygopalatine ganglion

10 maxillary sinus 11 infraorbital N 12a anterior communicating artery 12p posterior communicating artery

13 short ciliary Ns 14 falx cerebri 15 internal carotid artery

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SPECIAL SENSES

Neural pathways to and from the EYE CN III , IV & VI motor and CN V sensory Motor Nerves to the extra ocular muscles of the eye come from nuclei of CN III, IV & VI; Sensory feedback is received from the Ophthalmic division of the Trigeminal N = CNV1 The Light reflex comes for the parasympathetic imput from the accessory nucleus of CN III = Edinger–Westphal nucleus (IIIm)

1 intracerebral srcins 2 subarachnoid space 3 pathway through the cavernous sinus 4 cranial exit through the superior orbital fissure 5 extracranial pathway - orbital fossa 6 ciliary ganglion – site of synapse of the preganglionic parasympathetic fibres 7 level of the superior colliculus 8 level of the inferior colliculus 9 inferior border of pons and medulla oblongata 10 N to sphinter papillae CN III 11 Ns to levator palpbrae superioris & superior oblique CN III 12 Ns to inferior & medial recti + inferior oblique muscles CN III

13 Ophthalmic N = CN V1 and the 3 branches just before entrance into orbit Lacrimal Frontal -Nasociliary 14 N to superior oblique - CN IV = Trochlear N 15 N to Lateral rectus - CN VI = Abducens N

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SPECIAL SENSES

CN exits II, III, IV & VI Coronal section – muscular base of eye socket with enucleation - eyeball removed Coronal section – muscles sectioned showing BV, ligament support & N relations and boney cavity CNs III, IV & VI control the movement of the eyeball -mainly CN III, except for Superior Oblique CN IV and Lateral Rectus CN VI, for more details see the A to Z of the Head & Neck. CN II – is a special sensory N which reports the stimulation from the receptor cells in the retinas to the visual cortex. These diagrams demonstrate the exits of these Nerves and their interplay with other CNs such as CN V1 which is the sensory N for this area.

1 Recti muscles 4 in the eye i = inferior/ l = lateral / m = medial /s = superior 2 Optic N = CN II 3 Oculomotor N = CN III s = superior div. i = inferior div. 4 Trochlear N = CN IV 5 Ophthalmic vein i = inferior /s = superior 6 Abducent N = CN VI 7 Frontal N – branch of CN V1 8 Nasociliary N – branch of CN V1 9 Optic canal 10 Ophthalmic artery 11 Tendinous ring around the CN II and the artery 12 Lacrimal N – branch of CN V1 13 Oblique muscles i = inferior /s = superior 14 Levator palpabrae superioris 15 Superior orbital fissure – exit in the orbital cavity for the CNs & BVs 16 Trochea – ligamentous ring for superior oblique 17 Orbital cavity 18 Supraorbital notch 220

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SPECIAL SENSES

Neural pathways from the TONGUE CN VII, IX & X special sensory TASTE CN V3 sensory The special sensation of Taste is supplied by 3 CNs on the ispilateral side with overlap b/n these Ns. Other sensory feedback such as pressure and pain is supplied by the Mandibular N (CN V3), on the contralateral side.

1 ventroposteriomedical nuc of the Thalamus = arcuate and accessory arcuate nuclei of the Thalamus 2 solitariothalamic tract in the medical leminiscus 3 Bs 4 4th ventricle 5g Trigeminal ganglion 5n Spinal nucleus of CN V 5s Sensory fibres of the Mandibular N 7g Geniculate ganglion 7n Sensory nucleus of Nervus intermedius = upper portion of Nucleus solitarius 7ss Chorda Tympani fibres = special sense Taste fibres

8 Vallate papillae 9g inferior petrosal ganglion of CN IX 9s Gustatory nucleus (part of the Nucleus Solitarius – solitary tract) 9ss Special sensory fibres of CN IX - taste

10g nodose ganglion of CN X = inferior vagal ganglion 10s Solitary nucleus = Solitary tract = Solitary fasciculus 10ss Special sensory fibres of CN X - taste 38 Brodmann area for normal tongue sensation = uncus 40, 43 Brodmann areas for TASTE = Opercular Insular region in the CC

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SPECIAL SENSES

Taste areas on the TONGUE Tongue macroscopic view of the dorsal surface Taste bud histological section through the structure The special sensation of Taste is supplied by 3 CNs on the ispilateral side with overlap b/n these Ns. Within these areas supplied are subareas which recognize specific taste types. However there is considerable variation and overlap of these areas. The taste is detected via “taste buds” inserted into the stratified squamous epithelium of the tongue.

1 taste pore 2

microvilli

3

supporting cells = sustenacular cells

4 basal cell 5 sensory N 6 sensory N fibres inot the cells 7 sensory hair on cell surface Areas on the tongue detect certain tastes more sensitively they do not reflect the innervation A SWEET area B SOUR area C SALTY area D BITTER area CN VII

area innervated by the Chorda tympani ant. tip of tongue

CN IX

area innervated by the Hypoglossal N ant. 2/3 of tongue

CN X

area innervated by the Vagus N post. - 1/3 of tongue

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SPECIAL SENSES

CN VIII Auditory / Balance Pathways in situ Schema CN VIII the vestibulocochlear CN- conducts sensory information to the brain on sound, body position and balance. It is a special sensory CN. There is a crossover of the information as in most CNs, and extensive spread of the imput to many areas of the brain for interpretation and subsequent response.

A = CEREBRUM B = PARIETAL + TEMPORAL LOBES C = MIDBRAIN D = CN VIII pathway E = COCHLEA apparatus

1 transverse temporal gyrus 2 auditory radiation 3 medial geniculate body 4 inferior colliculus 5 superior olive 6 cochlear nuclei anterior + posterior 7 Pons 8 CN VIII fibres 9 spiral ganglion 10 middle ear = semicircular canals, ossicles, cochlea 11 basilar membrane of cochlea 12 parenchymal cells of cochlea 13 hair cells of cochlea 14 tectoral membrane

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SPECIAL SENSES

Vestibulocochlear N – CN VIII vestibular pathways = balance Balance is part of the special function of the Vestibulococchlear N. Hearing disorders are often accompanied by disturbance of balance (Meniere’s disease). Input from the vestibular apparatus in the middle ear goes to the 4 vestibular nuclei then to the thalamus & CC. It also goes directly to the cerebellum. The ocular Ns change the position of the eyeball to compensate for changes of head and body position.

1 to higher centres in CC 2 Thalamus VPM nucleus 3 CN III nucleus = oculomotor nucleus 4 CN IV nucleus = trochlear nucleus 5 medial leminicus 6 CN VI nucleus – abducens nucleus 7 medical longitudinal fasciculus a = ascending fibres / d = descending fibres 8g vestibular ganglia (CN VIII) – sensory input from vestibular apparatus of the middle ear = ampullae, saccule & semicircular canals 8n vestibular nuclei 4 inferior lateral medial & superior 9 fibres to cerebellum via inf. peduncle 10 lateral vestibulospinal tract

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CRANIAL NERVE EXAMINATION

Neurological examination General Considerations - in the Head & Neck When examining the neurological patient - look for: ASYMMETRY- muscle atrophy &/or hypertrophy, fasciculation, uneven facial features DEFORMITY - head held in a strained position / uneven posture /speech and swallowing difficulties TONE CHANGES - hyer-reflexia / spasticity / resistanceto passive movement / hypo-tonia / flaccidity / involuntary movements (also see the A to Z of Peripheral Nerves and the A to Z of the Head & Neck for full consideration of this area upper and lower motor syndromes and cerebellar dysfunction )

Cranial Nerve examination General When there is a lesion in the CN described – the following capabilities are lost -

ABDUCENS = CN VI Patient cannot abduct their eye - cannot look laterally on the affected side (Lateral Rectus) rarely seen in isolation generally associated with lesions of CN III, IV and V1. DD lesion of the Lateral Rectus muscle itself as in myopathies/muscle diseases note the eye which cannot move to look medially has the CN lesion – top image

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ACCESSORY = CN XI Patient cannot turn head or raise shoulders against resistance (Sternocleidomastoid + Trapezius)

FACIAL = CN VII Inspect the faceof-facial look for: asymmetry, blinking, lacrimation, salivation and evenness creases and lip movement on speaking. Patient has difficulty in using muscles of facial expression cannot whistle or blow through their cheeks, frown, raise their eyebrows, show their teeth, blink or close their eyes against R (muscles of facial expression). Taste is lost in the front of the tongue. Test by trying to open the tightly shut eye against R. DD Botx and other cosmetic procedures, myopathies Note : commonly seen unilaterally = Bell’s Palsy, associated with parotid gland pathology, idiopathic, commonly resolves spontaneously after2-3 weeks with children, but not with adults

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GLOSSOPHARYNGEAL = CN IX No feeling or reaction to touch on the soft palate and back of the throat absent Gag reflex - note 20% of normal people have a weak or absent GAG (Stylopharyngeus cannot be tested in isolation) very rarely seen in isolation generally associated with lesions of CN X particularly in eliciting the Gag reflex DD CN X lesions

HYPOGLOSSAL = CN XII Inspect the tongue - look for: atrophy, asymmetry, fasciculation and involuntary movements - Patient cannot move the tongue in and out evenly - will deviate to the side of the paralysis - nor push against the cheek and examiner’s finger strongly (Genioglossus and Linguali muscles) seen in isolation and associated with lesions of CN IX, X and XI DD drugs, chorea associated with psychiatric or mentalillnesses, motor neurone disease.

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OCULOMOTOR = CN III test eye movements - Patient cannot move eyes around follow an examiner’s finger with movements and sees double - eyelid may fall over the pupil and not be able to be elevated Range of eye movement possible is shown and all affected with CN III lesions even though 2 other CNs are involved in eye movements. (extrinsic and intrinsic eye muscles and Levator Palpabrae - not Lateral Rectus or Superior Oblique) seen in isolation and associated with lesions of CN IV, V1 and VI DD diseases of the eye muscles and myopathies

OLFACTORY CN I impaired or aabsent of smell to test - need strongsense stimulus cloves- difficult / peppermint

DD diseases of the upper respiratory tract note this is important to test when there are suspicions of lesions in the Anterior Cranial Fossa © A. L. Neill

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OPTIC = CN II inability to see / difficulty in seeing /inability to focus - test reaction to light - see light and accommodation reflexes DD diseases w/in the eyeball - cataracts, macula degeneration etc. if pathology is suspected go on to do evaluation of visual fields examination of the eye with the dilated pupil etc.

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TRIGEMINAL = CN V V1 absent sensation over the top half of the face - depending upon the lesion - may demonstrate onionskin pattern. absence of the corneal reflex

seen in isolation and associated with lesions of CN III, IV and VI DD diseases of the skin

V2 absent sensation over the mid and lower portions of the face

V3 cannot open jaw or move it side to side against resistance absent jaw jerk - note this is often absent in the young DD multiple sclerosis, pathology in the TMJ, dental abscesses and cavities, Herpes Zoster infections (this does infect V1 pathway and may leave permanent residual affects), tumours in the nasopharynx.

V1 V2

V3

Compression of Bs results in onion skin pattern Parasthesia © A. L. Neill

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TROCHLEAR = CN IV impaired eye movement - particularly cannot look up and out seen in isolation and associated with lesions of CN III, V1 and VI DD diseases of the eye muscles and myopathies note the eye which cannot move to look up and out has the CN lesion – top image

VAGUS = CN X inability to cough with pressure - long bovine cough asymmetry seen when examinig the larynx – say AHHH – observe uneven uvula (paralysis on the ipsilateral side) and presence of an husky voice seen in isolation and associated with CN IX and XII DD hysteria and lesions in the CNs IX or XII

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VESTIBULOCOCHLEAR = CN VIII ACOUSTIC component

loss of hearing – to test the frequencies impaired use tuning forks of different frequencies If there is better conduction through the bone than in the air – ie hold the fork against the mastoid – the hearing loss is CONDUCTIVE ie a block in the canal and not NEUROLOGICAL ie the N is intact A fork placed on the head midway should be heard evenly if this is not the case there may be unilateral hearing loss. DD diseases w/in the ear eg. wax blockage growth in the auditory tube

VESTIBULAR component nystagmus persisting after rapid change in the position of the head DD cerebellar diseases, viral infections of the brain or head region, pathology of the cervical region seen in isolation and associated with CN VII

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CRANIAL NERVE REFLEXES

Accommodation & Light reflexes (CN II, III, sympathetic fibres f rom T1 and 2 (Dilator Pupillae) Parasympathetic fibres from the ciliary ganglion (Sphincter Pupillae) Shine a light into one eye while shielding the other and pupils from both eyes should constrict, if only the stimulated pupil constricts - interruption in the Brainstem has occurred. Ask the patient to shift their gaze rapidly from one object to another at different distances in the room, closer objects cause pupillary constriction - presbiopia and cataracts may complicate interpretation of this reflex

1 Light stimulus 2 Sphincter Pupillae/Dilator Pupillae 3 Optic N tract, CN II 4 Edinger-Westphal part of oculomotor nucleus (CN III) 5 Pretectal nucleus (before the Thalamus) 6 pathway to Sympathetic chain T1, T2 (for Dilator Pupillae) 7 ciliary ganglion 8 Oculomotor N, CN III 9 postganglionic parasympathetic Ns = short ciliary Ns 10 object for focus 11 visual cortex 12 Optic radiation for interpretation 13 Lateral geniculate nucleus 14 Ciliaris -adjustment of lens and iris 15 Medial Rectus - one of the muscles moving the eyeball for better focus

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Blink reflex (CN V1 , VII) Tap the Glabella* region repeatedly and elicit blinking which will diminish after several taps (Orbicularis Oculi)

Corneal reflex (CN V1, VII) Approach the cornea from the side (out of sight by the patient) and touch lightly causing a blink (Orbicularis Oculi)

1 bright light 2 stimulus touching the cornea 3 Ophthalmic N - CN V 1 4 Optic N tract - CN II 5 Emotional imput / or response to sensation from higher centres 6 Visual reflex centres in the Midbrain 7 Facial N efferent fibres (CN VII) 8 Orbicularis Oculi + Levator Palpabrae Superioris * Forehead b/n the eyes.

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Crying/Lacrimation reflex (CN V1 , VII) (Orbicularis Oculi) Irritation to the eye directly - smell (eg. onion) or touch or indirectly via higher emotional centres will cause a reflex crying response.

1 stimulation of the cornea ± conjunctiva 2 stimulation from higher emotional centres 3a sympathetic chain 3b superior sympathetic ganglion 3c postganglionic fibres to the lacrimal gland 4 Ophthalmic N = CN V1 5 sensory nucleus of CN V 6 parasympathetic nucleus of CN VII (in the Pons) 7 Facial N = CN VII and pterygopalatine ganglion 8 Lacrimal gland

Sneezing reflex (CN V2 , X, C3,4,5 =Phrenic N + Intercostals T1-12) (Palatoglossus) Irritant to the nasal mucosaofstimulates a response to expel air in the region under pressure a closed Glottis - similar to thethe cough reflex but directed to go through to the nasopharynx by closing the oropharyngeal isthmus

1 CN V 2 Sensory nucleus of CN V in the brain stem 3 Motor nucleus of CN IX, X & XI 4 Respiratory centre 5 Phrenic N = C3,4,5 6 intercostal Ns 7 Ns to abdominal muscles 8 Vagus, Hypoglossal & Glosspharyngeal Ns (CN IX, X, XII) 242

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Stapedial reflex

(CN VIII, V3 higher centres)

When a person is about to speak and a sudden loud noise will cause the reflex contraction of Tensor Tympani

1 imput from higher centres - about to speak 2 loud irritating noise - afferent from CN VIII 3 somatic motor nuclei of CN V and VII 4 CN VII to Stapedius 5 Tympanic membrane

Salivation reflex

(CN I, II, VII, IX higher emotional centres, sympathetic and parasympathetic fibres) The thought, smell, sight or taste of food causing reflex secretion from the salivary glands

1 imput from higher centres - thinking of food 2 imput from seeing food Optic N = CN II - looking at food 3 imput from smelling food Olfactory N = CN I - smelling food 4a imput from tasting food Lingual N, ChordaTympani (CN VII) 4b & Glossopharyngeal Ns (CN IX) - tasting food* 5 Solitary nucleus of Medulla = Nucleus Solitarius 6a Salivatory centres of the Facial 6b & Glossopharyngeal nuclei 7 Preganglionic sympathetic cells (in the lateral horn of the SC) and fibres 8 Sympathetic chain 9 Postganglionic sympathetic fibres ("salivation) 10a Parasympathetic efferent fibres of CN IX and the Otic ganglion ("salivation) 10b Parasympathetic efferent fibres of CN VII and the Submandibular ganglion ( "salivation) 11 Salivary gland *note trained reflexes of timing and signals such as aural input can also influence the afferent stimulus to salivate - also both parasympathetic and sympathetic fibres increase salivation

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Swallowing reflex (CN IX, X, XII V3) a bolus of food or liquid - including saliva, placed at the back of the throat will cause the reflex initiation of swallowing

1 oropharynx 2 afferent fibres of Glossopharyngeal N (CN IX) 3 4 5 6 7

Solitary = Nucleus Solitarius Nucleusnucleus Ambiguus (motor nucleus of CN IX X & XII).. Vagus N (CN X) Hypoglossal N (CN XII) Preganglionic sympathetic cells (in the lateral horn of the SC) and fibres 8 Sympathetic chain 9 Postganglionic sympathetic fibres 10 interneuron connections stimulating peristalsis to the stomach 11 stomach

Gag reflex

(CN X)

irritation of the oropharynx / larynx w/o swallowing imput will cause coughing and gaging and if severe vomiting CN IX / X afferents will loop and efferent Ns will cause reflex reaction of coughing and muscle spasm (Pharyngeal Constrictors) diminished in 20% of people severely irritated - important to stop particles from going into unless the trachea

Jaw Jerk

(CN V3)

the mouth is opened slightly - strike the chin with a reflex hammer jaw will close and then open rapidly -monosynaptic stretch reflex (Masseter, Medial Pterygoid and Temporalis)

1 Temporalis 2 Masseter 3 4 5 6 7 246

Mandibular afferents (CN V3) Trigeminal ganglion Proprioceptive nucleus Motornucleus of Trigeminal N (CN V3) Efferents from Trigeminal N to muscles of mastication (CN V3) © A. L. Neill


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Carotid reflex (CN IX, X) Changes in the stretch receptors of the carotid sinus (BP) alter the level of the CO to regulate the blood volume passing through this area hence artificially stretching this body will cause a marked reduction in BF and fainting - VASOVAGAL reflex.

Yawning reflex (higher centres, CN V, VII, IX, X, XII Phrenic N and Intercostal Ns)

Observation - Mimicry, Boredom, Tiredness, Low O2 levels and/or High CO2 levels, will cause a reflex from the respiratory centre in the Medulla to increase the air intake rapidly by opening the mouth and pharynx very widely, contracting the diaphragm and increasing the rib cage -rapid relaxation follows - long expiration (Diaphragm, Platysma,Thyroid and Hyoid muscles, Pharyngeal muscles)

1 higher centres 2 Motor nuclei of several CNs including Trigeminal and Facial Ns (CN V3, VII) 3 Interneurons to Phrenic N (C3,4,5) 4 Interneurons to Intercostal Ns (T1-12) 5 Diaphragm (innervated by the Phrenic) 6 Intercostal muscles 7 Mandible - opened by muscle stimulation (CN X, XII) 8 Pharynx and Larynx opened (CN IX, X)

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THE SPINAL CORD

Fasciculus Cuneatus + Fasciculus Gracilis & Spinocerebellar tracts. Fasciculus Cuneatus (neck to mid Thorax=T6) + Fasciculus Gracilis (lower thorax =T7 - lower limb) = the Dorsal columns of the SC. Ascending sensory tracts for pressure, proprioception and touch to the sensory cortex of the CC or the cerebellum, the Dorsal columns.The ALS = anterolateral system. Note as with all sensory tracts there are 3 neurones needed to complete the pathway to the CC. (this also is present in the CNs)

1 1c 1g 2

axons of the 1st order neurones fasciculus cuneatus fasciculus gracilis axons of the 2nd order neurones

2c 3 4 5 6 7

M medial leminiscal tracts tracts – contralateral P==posterior spinocerebellar – ipsilateral fasciculus cuneatis axons of the 3rd order neurones thalamus CC midbrain cerebellum

8 pons 9 nucleus gracilis 10 nucleus cuneatus 11 MO 12 cell bodies of the 10 N located in the dorsal root ganglion 13 proprioreceptors receptors in muscle 14 touch – light touch receptors 15 lumbar SC 16 spinocerebellar tract note ipsilateral tract 17 cervical SC 18 dorsal root ganglion 19 post central gyrus 20 central sulcus 250

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THE SPINAL CORD

Lateral Spinothalamic tract Ascending sensory tracts for crude touch, deep pressure, pain & temperature to the sensory cortex of the CC. Note as with all sensory tracts there are 3 neurones needed to complete the pathway to the CC. (this also is present in the CNs)

1 axons of the 1st order neurones 2 axons of the 2nd order neurones = lateral spinothalamic tract 3 axons of the 3rd order neurones 4 thalamus 5 CC 6 midbrain 7 cerebellum 8 pons 9 nucleus gracilis 10 nucleus cuneatus 11 MO 12 dorsal root ganglion 13 pain receptors 14 temperature receptors 15 lumbar SC 16 lateral spinothalamic tract note crosses immediately to contralateral side

17 cervical SC 18 dorsal root ganglion 19 post central gyrus

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THE SPINAL CORD

Corticospinal tracts Descending motor tracts = anterior + lateral corticospinal tracts forming the main bulk of the Pyramidal tracts A collection of Axons b/n the motor CC and the SC, which travel through the internal capsule to the SC forming tracts in the anterior & lateral columns of WM in the SC.

1 motor CC 2 internal capsule 3 geniculate fibres 4 decussation of the pyramidal fibres 5a anterior cerebrospinal tracts 5L lateral corticospinal tracts 6 anterior N roots from the ventral / anterior horn 7 corona radiata

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THE SPINAL CORD

Pyramidal tracts Descending motor tracts passing through the pyramid formation of the MO = ant. & lat. corticospinal tracts + rubrospinal tract The smaller ant. tracts supply the skeletal muscles on the ipsilateral side. The larger lat. tracts and the rubrospinal tracts supply muscle on the contralateral side, crossing in the pyramids of the MO. The rubrospinal tracts are involved in maintaining muscle tone, coordination and balance. They do not have input from the CC, beginning at the red nucleus.

1 upper motor neurones 2 primary motor area of the CC 3 internal capsule 4 red nucleus 5 midbrain 6 cerebellum 7 pons 8 MO 9 decussation (crossing over) of lat. corticospinal fibres 10 SC cervical region 11 skeletal muscle 12 lumbar / thoracic SC 13 lower motor neurones – Spinal Nerves 14 anterior corticospinal tracts 15 lateral corticospinal tracts 16 rubrospinal tracts note extrapyramidal tracts are all the others ie which donot pass through the pyramids

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Pain Pathways – Nociceptor information Spinomesencephalic Spinoreticular & Spinothalamic tracts Ascending sensory tracts for pain or information from the nociceptors may include any sensory pathway – these are the main 3. Note they cross in the SC dorsal horns segments immediately upon entering.

1 axons of the 1st order neurones 2 axons of the 2nd order neurones 3 axons of the 3rd order neurones 4 thalamus 5 CC 6 midbrain 6g periaqueduct GM (in Midbrain) 6r reticular formation of the midbrain 7 cerebellum 8 pons 8r reticular formation of the pons 9 nociceptors or pain receptors 10 tracts in the SC for the pathways described 11 MO 11r reticular formation of the medulla 12 sensory N fibre entering ganglion where the N cell bodies are located synapse in SC dorsal horn - changes from 1o to 2o neurones 13 SC segments cervical, lumbar and/or thoracic 14 dorsal root ganglion

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Tracts of the SC* Transverse – thoracic Motor = Descending - carries messages to the body / muscles from the brain - efferent tracts = M = pure motor N

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Corticospinal tracts a = anterior / l = lateral = PYRAMIDAL TACTS

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motor CC ! skeletal muscles Reticulospinal tracts a = anterior / l = lateral reticular formation in the Bs! muscles for tone + visceral function

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Rubrospinal tracts* Red nucleus in MB ! distal flexor limb muscles for balance, posture & tone

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Olivospinal tracts

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Tectospinal MB !coordination of Head & Eye movements - “looking”

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Vestibulospinal* MO ! muscles for posture & balance

Sensory = Ascending - carries sensory input from the body to the brain / afferent tracts = S = pure sensory N

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Fasciculus gracilis – dorsal column from the lower thorax to LL

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Fasciculus cuneatus – dorsal column from the neck to the midthorax + UL Dorsal columns carry information regarding: - light touch, position, pressure & vibration to the sensory CC

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Spinocerebellar tracts a = anterior / p = posterior neuromuscular + neurotendinous information to the Cerebellum & Reflex arcs, to detect over stretching of muscle&/or tendons + feedback on balance & coordination

10 Spinothalamic tracts a = anterior / L = lateral crude touch, pain, pressure & temperature via the Thalamus to the CC M + S = PN = peripheral N generally a mixture of motor & sensory fibres.

For more detail on SC structure see the A to Z of Peripheral Nerves.

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Points of Immobility in the SC The Brain is connected to the SC and together they are a relatively immobile inelastic sensitive branched cord. Hence with changes in posture any tethered points place tension and so pain on this structure. As demonstrated this can be accentuated by various postures and so allow the clinician to locate and evaluate the areas of sensitivity for treatment. Green arrows ! demonstrate the direction of the pain when stretched and red arrows the direction of movement!

1 CN VII Facial N 2 boney canals in the mandible h = hypoglossal m = mandibular canal 3 commencement of the SC hindbrain / SC junction 4 SC 5 CN V Trigeminal N 6 midbrain 7 Femoral N 8 Saphenous N 9 Sciatic N

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Relation of the ANS / sympathetic chain to the SC and VC The sympathetic chain of the ANS flanks the thoracic region of the VC forming ganglion opposite each thoracic outlet and feeding fibres into the visceral region. In the cervical region these coalesce into 3 major ganglia and in the lumbar region they lie across the VB of the VC.

1 superior cervical ganglion 2 middle cervical ganglion 3 lower cervical ganglion 4 sympathetic chain 5 visceral branches 6 VB of L2

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Relations of the Cervical Sympathetic Trunk & Ganglia Note Horner’s syndrome is due to an interruption of the cervical ganglia = miosis + ptosis + enophthalmus + vasodilatation + anhydrous

1 Vertebral artery 2 internal carotid N 3 Superior cervical ganglion 4 Middle cervical ganglion 5 Inferior thyroid artery 6 Thyrocervical trunk 7 Subclavian artery 8 Stellate ganglion (C4-T1 fusion) 9 2nd thoracic ganglion 10 vertebral N 11 communicans b/n cervical Ns 12 loop of Atlas 13 fibres to CN XII 14 fibres to CN X 15 fibres to CN XII in the descending loop ansa cervicalis

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The A to Z of The Brain

Dr EILL BSc MSc MBBS PhD FACBS Dr.. A. A. L. L.NNEILL [email protected] or www.amandasatoz.com mobile 0410 018 681 Contact www.aspenpharma.c om.au for login and pass words www.aspenpharma.com.au passwo rds for the complete A to Z and the AspenAtlas online. Aspen Pharmacare Australia Pty Ltd 34-36 Chandos Street Street,, St St Leonards NSW 2065 ABN 51 096 236 985

50640309 a to Z of the Brain Web Version

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