NEUROANATOMY NOTES - Epomedicine
NEUROANATOMYNOTESBy Dr. Sulabh Kumar Shrestha
CHAPTER1How to Draw MidbrainCross-section?The cross-section of midbrain can be comparedupside down striped face of a red-eyeddemon7. Whiskers Cranial nerves CN III towards head CN IV towards chin8. Stripe Lemniscus Towards head Medial lemniscus Middle Spinal lemniscus(Spinothalamic tract) Towards chin Lateral lemniscus9. Zygoma Medial geniculate body10. Mouth Cerebral Aqueduct11. Lips Peri-aqueductal grey12. Angle of mouth Mesencephalictrigeminal nucleusthe structures found on the cross-section ofmidbrain:1. Ear Crus cerebri Medial frontopontine fibers Middle corticonuclear andcorticospinal tract Lateral temporopontine fibers13. Chin Colliculus Superior colliculus in superior section Inferior colliculus in inferior sectionNow,label them:2. Eye brows Substantia nigra3. Red eyes Red nucleus4. Bridge of nose Raphe nucleus5. Ala of nose Median longitudinalfasciculus (MLF)6. Nostrils Cranial nerve nucleus CN III in superior section CN IV in inferior sectionAnother important mnemonic that everyonemust remember is that: Motor tracts aretowards Midline and Sensory tracts aretowards Side.1
CHAPTER2How to Draw Pons CrossSection?The cross-section of pons is similar to themidbrain as described earlier but few thingsmust be kept in mind:1. The orientation of lemnisci in midbrain ismore or less vertical, but in pons it ishorizontal.2. Cranial nerve III and IV arises frommidbrain and mainly Cranial nerve V, VI,VIII and VIII arises from pons.3. Cerebral aqueduct lies in midbrain and4th ventricle lies in pons.Wa humanoMedially: Medial lemniscusoMiddle: Trigeminal lemniscus mediallyand Spinal lemniscus laterallyoLateral: Lateral lemniscus5. Bridge of nose Raphe nucleii6. Ala of nose Medial LongitudinalFasciculus7. Mole Facial nerve motor nucleus (Incaudal pons)8. Moustache Cranial nerve nucleiioMedial most CN VI or Abducensnerve (In caudal pons)oMiddle CN V or Trigeminal nervemotor and sensory (In rostral pons)oLateral most CN VIII Superiorvestibular nucleus (In rostral pons)inverted face of-section of pons.9. Lips Periventricular grayoContains locus coeruleus10. Open mouth 4th ventricle11. Chin Superior cerebellar peduncle1. Hair Transverse pontine fibers2. Eye Corticospinal and Corticonucleartracts3. Ear Middle cerebellar peduncle4. Stripes Lemnisci2
CHAPTER3How to Draw MedullaOblongata Cross-section?Like in Midbrain and Pons:1. Corticospinal tract passes ventrally.2. Ventricular system is dorsal in midline.3. Cranial nerve nuclei are located justanterior to the ventricle.4. Medial longitudinal fasciculus is presentaround the center.Caudal medulla resespinal cord1. Circular in shape2. Draw another pair of circles anteriorlyoInferior olivary nucleus3. Draw a triangle in the center between 2posterior circleso4th ventricle4. Draw a pair of triangles anterior to the 2anterior circlesoPyramids5. Draw a boomerang just anterior to thetriangle representing 4th ventricleoPeriventricular gray6. Draw another boomerang anterior to theprevious boomerang2. Central canal instead of 4th ventricleo3. Nucleus gracilis and nucleus cuneatusdorsally4. Pyramids and medial lemnisci decussateCranial nerve nucleii (from medial tolateral) CN XII Dorsal vagal nucleus Nucleus tractus solitarius Medial vestibular nucleus Posterior cochlear nucleus7. Draw a pair of rectangles in the centeroHow to draw medulla cross-section?1. Draw a pair of circlesoInferior cerebellar peduncleRepresents medial lemniscus(anteriorly) and Medial LongitudinalFasciculus (MLF) posteriorly8. Draw a pentagon with apex tiltedmedially, just anterior to the posterior pairof circles the 5 points of the pentagonrepresents 5 structures (starting from apexin clockwise fashion)oNucleus ambiguusoTrigeminal nerve nucleus and spinaltract3
CHAPTER3oAnterior cochlear nucleusoAnterior spinocerebellar tractoLateral spinocerebellar tractoLateral spinothalamic tract inside thepentagonNow, look how a real cross-section would ray694.pngHenry Vandyke Carter [Public domain]4
CHAPTER4oSpinal Cord Cross-sectionand Tracts Simplified2nd crossing in the cerebellumC. 2 Anterior Tracts:The fibers of these tracts cross at the level ofspinal cord:1. Anterior corticospinal tract2. Anterior and Lateral spinothalamic tractD. Extrapyramidal tracts:1. Rubrospinal tract (Cross at midbrain)2. Vestibulospinal tract: Uncrossed3. Reticulospinal tract: UncrossedOrganization of Ascending and DescendingTracts in Spinal Cord4. Olivospinal tract: UncrossedA. 2 Posterior Tracts:The fibers of these tracts cross to the oppositeside at the level of medulla:1. Dorsal column (Cross at medulla)oFasciculus gracilisoFasciculus cuneatus2. Lateral corticospinal tract (Cross atmedulla)B. 2 Lateral Tracts:The fibers of these tracts remain on ipsilateralside:1. Dorsal spinocerebellar tract (Do notcross)2. Ventral spinocerebellar tract (Crosses 2times to lie on ipsilateral side)oNow, look at the somatotropic arrangement ofthe various tracts: Fasciculus gracilis: lower limbs Fasciculus cuneatus: upper limbs Corticospinal tract: upper limbsmedially and lower limbs laterally Spinothalamic tract: upper limbsmedially and lower limbs laterall1st crossing in the spinal cord5
CHAPTER5Vertebrobasilar ArterialSystem and SyndromesCourse:1.Ascends through transverse foramina onC6 through C1 and enters posterior fossathrough foramen magnum2.Continue up the ventral surface ofmedulla3.Converge at the ponto-medullary junctionto form single basilar artery4.Branches are given inside cranial vault,once it has entered through foramenmagnumVertebral ArteryI use the analogy of hand to remember thevertebral artery and its branches:Supplies: Spinal cord, Medulla and InferiorcerebellumBranches:1. Anterior spinal artery (Single artery): Run down the front of the spinal cord Supplies ventrolateral 2/3rd of cervicalspinal cord and ventrolateral medulla2. Posterior spinal arteries:Index and ring fingers Vertebral arteries of 2sides; Middle finger Anterior spinal artery;Thumb and pinky fingers Posterior InferiorCerebellar Artery (PICA) of 2 sides; WristPontomedullary junction where 2 vertebralarteries converge; Forearm Basilar artery;Remember if there is anterior spinal artery, thereis also posterior spinal artery (not shown here)which can arise wither from vertebral artery orPICA. Bilaterally run down dorsolateral tospinal cord Supplies posterior 1/3rd of cervicalspinal cord and posterior medullaClinical Correlate1. 10 medullary arteries arising from segmentalbranches of aorta feeds anterior and posteriorspinal artery along their course. In lowerthoracic/upper lumbar region, large segmentalartery exists and usually on Left side named asdue to its lower thoracic/upper lumbar location.Origin: Branch of subclavian arteries6
CHAPTER52. Anterior spinal infarct can only affect the armfibers of the lateral corticospinal tracts withoutaffecting the leg fibers and vice versa (a posteriorspinal artery infarct can affect the leg and not thearm fibers), because the border of the anteriorand posterior spinal arterial territorieslies within the corticospinal tract systems in thelateral funiculi.3. Occlusion of vertebral artery or Anteriorspinal artery can result in Medial medullary or.3. Posterior Inferior Cerebellar Artery (PICA): Supplies all of medulla except anteromedian part Supplies all of the inferior cerebellum andmedial part of middle cerebellumClinical Correlate: PICA injury leads to PICAor Wallenberg Syndrome.4. Meningeal branch: Supplies falx cleof Willis en.svgAttribution: Rhcastilhos [Public domain]Basilar ArteryClinical correlateOrigin: Joining of 2 vertebral arteries at pontomedullary junctionObstruction of basilar artery damaging thebilateral ventral pons give rise to Locked-inSyndrome. Because the tegmentum of the ponsis spared, the patient has a spared level ofconsciousness, preserved vertical eyemovements, and blinking. The corticospinal andcorticonuclear tracts are affected bilaterally. Theoculomotor and trochlear nerves are not injured.Patients are conscious and may communicatethrough vertical eye movements.Course:1. Ascends along the midline of pons2. Terminates near rostral border of pons bydividing into 2 Posterior cerebral arteriesSupplies: Pons, Anteroinferior and superiorcerebellum and Inner ear7
CHAPTER5Branches:Clinical correlateSince, there is Posterior Inferior CerebellarArtery there must also be Anterior InferiorCerebellar Artery (AICA) and SuperiorCerebellar Artery (SCA). The branches fromdown to up are:Occlusion of paramedian branches of basialartery results in Medial pontine syndrome(Foville syndrome). This is similar to medialmedullary syndrome but can be localized by thefindings of CN VI (medial strabismus due tolateral rectus paralysis and lateral gaze paralysisif PPRF is involved) and VII lesions (LMN typeof facial palsy).1. AICA: Supplies dorsolateral part of caudal ponsand antero-inferior region of cerebellum Gives rise to labyrinthine artery in 85%casesClinical correlateOcclusion of AICA can result in LateralPontine Syndrome or Marie-Foix syndrome.It is similar to Lateral medullary syndrome butcan be localized by lesions of CN VII, CN VIIIand other nucleus of CN V except spinal nucleusof CN V which is also injured in medullarysyndromes. AICA occlusion is more specificallylocalized by presence of CN VII and CN VIIIlesions as it is present in the caudal pons.2. Labyrinthine artery: Usually originates from AICA but canoriginate from the basilar artery Follows the course of CN VIII andsupplies the internal ear3. Pontine branches: Supplies anterior and lateral part of ponsthrough paramedian and circumferentialbranchesOcclusion of the paramedian andcircumferential branches can result in Ventralpontine syndrome (Millard-Gubler Syndrome).It presents with contralateral limb weakness(corticospinal tract involvement) and ipsilateralCN VI and VII defects.4. Superior cerebellar artery (SCA): Supplies dorsolateral part of rostral ponsand caudal midbrain Supplies superior cerebellum and lateralregion of mid-cerebellumClinical correlateOcclusion of SCA can result in Lateral PontineSyndrome or Marie-Foix syndrome. It issimilar to Lateral medullary syndrome but canbe localized by lesions of CN VII, CN VIII andother nucleus of CN V except spinal nucleus ofCN V which is also injured in medullarysyndromes. SCA occlusion is more specificallylocalized by presence of CN V lesions as it ispresent in the rostral pons.5. Posterior cerebral arteries: Paramedian and circumferential branchessupply the midbrain.8
CHAPTER5 Forms circle of willis to supply brainClinical correlate:Occlusion of posterior cerebellar arteries canresult in Medial midbrain syndrome (Webersyndrome). It is characterized by contralaterallimb weakness (corticospinal tract involvement),contralateral lower facial weakness(corticobulbar fiber involvement i.e. UMN typeof facial palsy) and ipsilateral CN III lesion.Parinaud syndrome (Dorsal midbrainsyndrome): This is caused due to pineal tumorcompressing the superior colliculi. It compressesthe vertical gaze center at the rostral interstitialnucleus of medial longitudinal fasciculus(riMLF) leading to vertical gaze palsy. It isaccompanied by bilateral pupillary abnormalitiesand signs of elevated ICP (cerebral aqueductcompression).Arterial Supply of Brainstem9
CHAPTER6Circle of Willis – Mnemonicand DrawingCircle of Willis is an important arterialcommunication that supplies the forebrain(telencephalon, diencephalon and optic vesicle)and often frequently tested in the exams. Circleof Willis receives blood from:Step-wise instructions for drawing the circleof Willis:1. Draw a Circlearteries.Circle of Willis is a circle ofWillisWthis represents Posterior Cerebral Arteries(PCA) which arises from a single basilar artery.1. Vertebrobasilar system: Basilar arterywhich gives off Posterior Cerebral Arteries(PCA) and Posterior communicatingarteries which are the branches of PCA2. Internal Carotid Artery System: Givesoff other arteries of Circle of WillisHere, we will learn a mnemonic to draw thecircle of Willis and intracranial course ofInternal Carotid Artery (ICA).3. Write aat the sides of the circlethis represents Middle Cerebral Artery(MCA) outside the circle and Internal CerebralArtery (ICA) inside the circle.llthisrepresents the Anterior Cerebral Arteries(ACA) along with the part of circle between theMCA-ICA and Anterior communicating artery.5. Write aat the sides of the circlethis represents Middle Cerebral Artery10
CHAPTER6(MCA) outside the circle andInternal CerebralArtery (ICA) inside the circle.Now, the intra-cranial course of InternalCarotid Artery:6. Write astartingfrom carotid canal and ending in foramenlacerum.7. Write another horizo starting from foramen lacerum and then siphon within cavernous sinus and then ending at the level of anterior clinoidprocess supraclinoid segment of ICA gives ofbranches to form Circle of Willibeginning fromhttps://commons.wikimedia.org/wiki/File:Circle of Willis 5.jpgAnatomist90 [CC BY-SA 3.0 1
CHAPTER7Circle of Willis and BloodSupply of ForebrainGeneral Concepts of Blood Supply ofBrain and Spinal Cord1. Spinal cord, Hind-brain and Midbrain: Veterbro-basilar system2. Forebrain: Circle of willis which comprises of: Vertebrobasilar system: Posterior Cerebralcommunicating artery Internal carotid system: Other arteries ofcircle of willis including Anterior CerebralArteries (ACA), Middle Cerebral Arteries(MCA) and Posterior Cerebral Arteries(PCA)Forebrain derivatives are Telencephalon,Diencephalon and Optic vesicle.3. The major vessels have 2 branches: Leptomeningeal branches: supplysuperficial regions (cortical andsubcortical regions) Perforating branches: supply deepstructures like diencephalon, basal gangliaand internal capsule)4. Segments of the arteries: Proximal segments (A1 of ACA and P1 ofPCA) are proximal to the respectivecommunicating arteries, i.e. Anteriorcommunicating artery and Posteriorcommunicating artery respectively. Proximal segment of MCA (M1) isproximal to the bifurcation of trifurcationof the artery. Distal segments (A3 of ACA, M4 of MCAand P4 of PCA) are the cortical segmentsthat supply the cortex.Territories of Major arteries of Circle of WillisICA enters through carotid canal to thecavernous sinus as shown in picture above.5. Leptomeningeal territories of arteries ingeneral: PCA: supplies posterior and inferiorsurfaces ACA: supplies antero-medial surface MCA: supplies lateral surfaceLocation of Circle of WillisThe arteries get interconnected around theinterpeduncular fossa which is a rhomboid(diamond) is shaped space in the ventral surfaceof the brain formed by the 2 Optic tractsanteriorly and 2 cerebral peduncles from ponsposteriorly. It encloses tuber-cinerum,mammillary bodies, posterior perforatedsubstance and the occulomotor neve fromanterior to posterior.Interpeduncular cistern or Basal cistern Interpeduncular fossa Cerebral peduncles Circle of Willi12
CHAPTER7Importance of Circle of Willis: Collateralcirculation4. Caudate nucleus head, anteromedial andinferior basal ganglia, anterior limb andgenu of inferior internal capsuleAnterior Cerebral Artery (ACA)Middle Cerebral Artery (MCA)ACA runs in the interhemispheric fissure andarches anterior to the genu of corpus callosumand then along the cingulate sulcus to give offbranches.Remember: The course of ACA is moreon medial and hence, have major supplyon medial brain surface and also givesof medial striate branch as deep perforatingbranch.Supplies:1. Medial surface of cerebral hemispheres2. Medial, infero-medial and supero-lateralparts of frontal lobe and medial parietallobe3. Corpus callosum except spleniumMCA courses laterally on lateral sulcus orsylvian fissure (overlies the insula) and emergesout on the lateral surface of the brain.Suprasylvian branches supply lateral and inferiorfrontal lobe and anterior lateral parts of parietallobe. Infrasylvain branches supply lateraltemporal lobe including its anterior tip and theamygdala and posterior parietal.Remember: The course of MCA is moreon lateral and hence, have major supplieson lateral brain surface and also gives lateralstriate branch as deep perforating branch.Supplies:1. Supplies lateral portion of basal ganglia.2. Superior surface of whole internal capsule13
CHAPTER73. Anterior temporal lobe and most of thelateral surface of the cerebral hemispheresPosterior Cerebral Artery (PCA)PCA courses backwards, beneath the spleniumof corpus callosum, to the calcarine fissure andto the lateral occipital surface. Posterior part of caudate nucleus andputamen Choroid plexus of anterior part of lateralventriclesDeep Perforating Branches andBlood Supply of Basal Ganglia andDiencephalonRemember: The course of PCAis backwards and hence, have major supply onthe posterior brain surface. It givesthalamoperforating artery, thalamogeniculateartery and posterior chorodial artery as deepbranches to supply the thalamus.Supplies: Medial surface of parietal lobe Medial and inferior surface of temporallobe including hippocampal formation Occipital lobe Splenium of corpus callosum Choroid plexus of ventricles Thalamus, hypothalamus and subthalamicnuclei MidbrainAnterior Choroidal ArteryBranch of Internal Carotid Artery (ICA). Itsupplies: Posterior limb of inferior part of internalcapsule Anterolateral thalamus Globus pallidusCircle of Willis LesionsBerry AneurysmsCommonest site is the branch point betweenanterior communicating artery and anteriorcerebral artery (40%). Other common sites arethe bifurcations/trifurcations of MCA (34%) andjunction between posterior communicatingartery and MCA (20%).Branching points are the sites where arterialmedia are congenitally attenuated.Remember the relations in interpeduncularfossa: Aneurysms in anterior communicatingartery: compresses the optic tract (visual14
CHAPTER7field defect bitemporal lowerquardantopia)Aneurysms in the posterior communicatingartery: compresses the occulomotor nerve (CNIII palsy down and out eye)Watershed ZonesWatershed zones are the border zones thatreceive dual blood supply from terminal or distalbranches of the 2 large arteries. Strokes in theseareas (watershed stroke or infarction) occursduring severe hypotension when the cerebralautoregulation fails and these border zones arestarved of blood. can understand the command Callosal lesion: disconnection ofWerncortex cannot execute left arm movementon command. left primary motor cortex intact: canexecute a command to move right armMiddle Cerebral Artery (MCA)MCA supplies the lateral convexity (parietalregion) of the brain including:1.The somatotopic sensorimotor area betweenthe middle and anterior cerebral arteries encodesthe proximal arms and legs. So patientswith watershed strokestrouble lifting their arms and legs but theirhands and feet are fine.2. Arcuate fasciculus or Superior longitudinalfasciculus3. Sensorimotor homonculus of remainingareas, i.e. face and arms4. Frontal eye field5. Splenium of corpus callosumLesion leads to:Anterior Cerebral Artery (ACA)The sensorimotor homnculus for leg and footare in the paracentral lobule in the medial aspectof brain. Hence, the lesion leads to contralateralleg-foot motor and sensory loss.ACA also supplies the majority of anteriorportion of corpus callosum, the damage of whichleads to transcortical apraxia (a disconnectsyndrome). There is no motor weakness, but thepatient cannot execute a command to movetheir left arm.1. Contralateral face and arm paralysis andsensory loss2. Dominant hemisphere (Speech centers):Aphasia3. Non-dominant hemisphere (Supramarginalgyrus and angular gyrus body and spatialawareness): Contralateral hemisensoryneglect15
CHAPTER7Posterior Cerebral Artery (PCA)Supplies occipital cortex, diencephalon androstral midbrain.Lesion leads to contralateral homonymoushemianopia with macular sparing and alexiawithout agraphia if the lesion is on left side(dominant hemisphere). Alexia results as thevisual information from intact right (nondominant) cortex is blocked by the lesion andcannot reach the language area. This is due todamage of splenium of corpus callosum.Lateral Striate ArteryBranch of MCA which supplies the anterior limbof the internal capsule (supply superior portionof internal capsule including posterior limbwhich project corticospinal fibers) and ventralthalamus (relays sensory tracts). Isolated infarction of internal capsule: Puremotor stroke (contralateral hemiparesis) Isolated infarction of thalamus: Puresensory stroke (contralateral sensory loss16
CHAPTER8Dural reflections andVenous sinusesanterolaterally and to the occipital boneposterolaterallyoDura mater (pachymenix) is the outer meningeallayer consisting of:1. Outer endosteal/periosteal layer: Firmlyattached to the periosteum of the calvarium2. Inner meningeal layer: Gives rise to duralreflections and continues into foramenmagnum as spinal durafalx cerebri is attached to the tentoriumcerebelli and pulls it up tent likeappearance2. Diaphragma sellae (Sellar diaphragm):Extends between anterior and posteriorclinoid processesopartially covers the pituitary glandallowing the infundibulum and vesselsDura is pain sensitive:Dural ReflectionsThese are the infoldings formed by the innermeningeal layer reflecting away from the fixedperiosteral dural layer.Two vertical reflectionsand left hemisphere:Separate the rightDura is sensitive to pain, especially where it isrelated to the dural venous sinuses andmeningeal arteries. Headaches can occur due tostimulation of the sensory nerve endings in thedura. It is innervated by all 3 divisions of thetrigeminal nerve, sensory fibers of C2, C3 andmeningeal branches of CN X and CN XII.1. Falx cerebri (Cerebral falx): Extends fromcrista galli of ethmoid bone anteriorly toinner occipital protuberance posteriorlyand projects over longitudinal cerebralfissure.Epidural hematoma:2. Falx cerebelli (Cerebellar falx): Extendsfrom tentorium cerebelli superiorly toinner occipital protuberance inferiorly inthe posterior cranial fossa.Tearing of the dura separates bone & periosteallayer of dura creating an epidural spaceTwo horizontal reflections:Rupture of high-pressure arteries (middlemeningeal artery) running through the duramaterthe duralattachments provide more resitance to thecollected blood to spread along than theunderlying brain which get compressed1. Tentorium cerebelli (Cerebellar tentorium):oseparates cerebellum and brainstem fromcerebrum (occipital lobes)oattached to clinoid process anteriorly,upper edge of petrous temporal bonehematoma isbetween the periosteal sublayer and the bone.Cross the dural reflections hematoma isoutside the periosteal sublayerMay have a lucid interval17
CHAPTER8Dural Venous SinusesShearing of low-pressure bridging veins is allthat is necessary to create a subdural hematoma.1. Superior sagittal sinus: lies at the superiorattached border of falx cerebriSubdural space is actually filled with the looselyarranged dural border cell sublayer. Pathologicbleeding into the border cell sublayer creates asubdural fluid space; otherwise, no true spaceactually exists. Receives blood from superior cerebralveins (bridging veins) and emissary veins(connects extracranial venous system withintracranial venous sinuses potentialroute of infection).the underlying brainprovides more resistance to the collected bloodthan the loosely arranged dural border cellsallowing it to spread along Receives CSF from arachnoidgranulations.Crosses the suture line as it is unaffectedpool at the siteof dural reflections2. Inferior sagittal sinus: lies at the inferior freeborder of falx cerebri3. Straight sinus: lies at the line of attachmentof falx cerebri and tentorium cerebelli Formed by the union of inferior sagittalsinus and the great cerebral vein o 1909 589.pngDr. Johannes Sobotta [Public domain]18
CHAPTER84. Occipital sinus: lies in the attached border oftenorium cerebelli Receives venous blood from superior andinferior ophthalmic veins, superficialmiddle cerebral vein and sphenoparietalsinus. Drains into superficial and inferiorpetrosal sinuses.Communicates inferiorly with the internalvertebral venous plexus.5. Confluence of sinuses (torcularHerophili): It is lies at the inner occipitalprotuberance and is formed by the union of: Superior sagittal sinus Straight sinus Occipital sinusIt drains into the transverse sinuses.6. Transverse sinuses: runs transversely at theposterolateral margin of tentorium cerebelli Drains venous blood from transverse sinusinto the sigmoid sinus. Normally, one transverse sinus can besmaller than the other usually the left islarger.7. Sigmoid sinus: as the name suggests, itinferomediallyfrom the transverse sinus (parietal to temporalbone) and then anterolaterally (temporal tooccipital bone) into the jugular foramen where itcontinues as Internal Jugual Vein (IJV). forms deep grooves in the bones along itscourse8. Cavernous sinus: The inter-cavernous sinuses lie on thebody of sphenoid. These connect thecavernous sinuses of the 2 sides which sitson the side of the body of sphenoid. It contains the siphon of Interncal CarotidArtery (ICA).9. Superior petrosal sinus: runs along petrouspart of temporal bone (anterolateral attachmentof tentroium cerebelli) Drains cavernous sinus into sigmoid sinus10. Inferior petrosal sinus: runs in the groovebetween petrous temporal bone and basilaroccipital bone Drains cavernous sinus into sigmoid sinusBasilar venous plexus: lies over the basilar partof occipital bone and connects the 2 inferiorpetrosal sinuses and communicates with theintervertebral venous plexus.Dural Venous Sinus ThrombosisVenous occlusion presents with a myriad ofsymptoms with variable severity. Sometimes thesymptoms are as mild as simpleheadaches and othertimes they are severeenough to produce confusion, stupor, or evencoma, along with paralysis and other focalneurologic deficits. Superior sagittal sinus or thedominant transverse sinus thrombosis can affectthe arachnoid granulations absorption ofcerebrospinal fluid, a consequently increase ofcerebral swelling may occur. The subsequentvenous hypertension can lead to oedema, andeven haemorrhage.19
CHAPTER9Microanatomy of CerebralCortex3. InsulaNeurons of the cortex:1. Pyramidal cells:The neocortex have 6 layers and allocortex haveonly 3 layers.The 6 layers of Neocortex:oLarge layer V pyramidal cells projectaxons to brainstem and spinal cord.oSmaller layer II and III pyramidal cellsproject axons to other cortical areas.Orientation of layers: Outer: Towards meninges Inner: Towards white matterIdea about the layers: Molecular or plexiform: Only cell processes Granular layer: Densely packed stellate cells Pyramidal layer: Medium and Largepyramidal cells Multiform layer: Different types of cells Pyramidal cells are absent in inner granularlayerThe 3 layers of Allocortex:2. Stellate cells: Interneurons whose axonsremain within the cortex3. Fusiform cells (in deeper layers): Gives riseto corticothalamic projections4. Horizontal cells of Cajal5. Cells of MartinottiBands of Baillarger: Formed by highconcentration of horizontally arranged nervefibers. External band: In layer IV Internal band: In layer V1. Molecular layer2. Pyramidal layer3. Multiform layerAllocortex is found in: Limbic system1. Olfactory cortex2. Hippocampal formation3. SubiculumMesocortex: A transitional type of 3 to 6layered cortex between neocortex and allocortex1. Parahippocampal gyrus2. Pre- and Para-subiculum20
CHAPTER9Schematic Diagram and Connection21
CHAPTER10Brodmann Areas andLesions Lesion: Contralateral horizontal conjugategaze palsyArea 44 (Inferior frontal gyrus; parsopercularis) and Area 45 (Inferior frontalgyrus; pars triangularis):speech center only in Dominant hemisphere) Lesion: Comprehends language well butfails to express thoughts verbally or inwrittenoNonfluent, motor or expressiveaphasiaoAgraphia (inability to write)Areas 9, 10, 46 (Prefrontal cortex) and Area11, 47 (Orbitofrontal cortex): Part of limbicsystem regulating emotions and higher mentalfunctions. Area 11 is associated with i/File:Brodmann areas.jpgAttribution: Vysha [CC0] Frontal LobeArea 4 (Precentral gyrus): Primary motorcortex (gigantopyramidal only area thatcontains giant pyramidal cells of Betz) Lesion: Contralateral spastic paralysis(UMNL)Area 6 (Superior frontal gyrus; agranularfrontal): Premotor cortex and Supplementarymotor cortex (Motor planning) Lesion: Apraxia (Unable to performmovements in correct sequence)Area 8 (Middle frontal gyrus; intermediatefrontal): Frontal eye field (Contralateralhorizontal conjugate eye movements)Lesion: Deficits in concentration,orientation, abstracting ability, judgement,problem-solving ability, loss of initiative,inappropriate behavior, frontal release ofsucking and grasping reflexes.Parietal LobeAreas 3,1 and 2 (Postcentral gyrus): Primarysomatosensory cortex (Discriminative touch,vibration, position sense, pain and temperature) Lesion: Impairment of all somaticsensations in contralateral side of body.Area 43 (Inferior parietal lobule, just belowsomatosensory cortex in postcentralgyrus): Primary gustatory area (sensory)Areas 5 and 7 (Superior parietallobule): Somatosensory association cortex22
CHAPTER10(Spatial awareness and Awareness of body ingeneral) Lesion: Contralateral astereognosis andsensory neglect (damage in nondominanthemisphere)oContralateral hemianopia or lowerquadrantanopia (pie in the floor). Lesion in non-dominant hemisphere:Area 40 (Inferior parietal lobuleSupramarginal gyrus) and Area 39 (Inferiorparietal lobule Angular gyrus): Multimodalassociation areas that receives input from visual,auditory and tactile modalitiesThese areas are als
medullary syndrome but can be localized by the findings of CN VI (medial strabismus due to lateral rectus paralysis and lateral gaze paralysis if PPRF is involved) and VII lesions (LMN type of facial palsy). Occlusion of the paramedian and circumferential branches can result in Ventral pontine syndrome (Millard-Gubler Syndrome).
Functional Neuroanatomy Here we argue functional neuroanatomy for pos . The basal ganglia may also contribute to the modu-lation of each process though its gamma-aminobu-
neuroanatomy: Functional anatomy – Neural structures that serve particular functions; e.g., pain path from skin to cortex for perception Regional anatomy – Localization of structures in particular brain regions Dual approach to learning neuroanatomy: Functional anatomy – Neural structures that serve particular
Neuroanatomy Guide Neuroanatomy is bewildering when first encountered. In the mass of structures and connections, it is hard to differentiate between critical and trivial facts. In this course, . little mixing occurs via this system and the anatomy i
220 P. Ward et al. / Functional neuroanatomy and behavioural correlates of the basal ganglia Fig. 1. Frontal-subcortical loop: the basal ganglia integrate information from a wide range of cortical areas, and feed back to selected frontal regions via the thalamus. however has demonstrated that the basal ganglia are
1 Functional Neuroanatomy PART I. INTELLECTUAL FOUNDATION OF PSYCHIATRY Cerebrum Cerebral cortex Basal ganglia Olfactory bulb (CN I) Amygdala Basal ganglia Caudate Cingulate Globus pallidus Heschl’s gyri Hippocampus Rolandic fissure Sylvian fissure Limbic system Nucleus accumbens Prefrontal cortex
The consequences of damage to the pre frontal cortex, anterior basal ganglia, and related structures. The significance of the principle of the paradox of assessing and . Executive functions: Functional neuroanatomy and clinical applications Author: Hoepner, Jerry K.
Gross Neuroanatomy . Overviews of the Cerebral Cortex, Hippocampus, Cerebellum, Basal Ganglia . Textbook, chapter 1 5 . Week 2 Functional organization of perception, Chapter 1 6 (5. th ed.) Internal representations of Space and Action , Chapter 17 (5. th. ed), cont. Integration of sensory and motor function, chapter 18, 19 . Week 3 Exam 1
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