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Home , Basket cell, Cerebellar hemisphere, Cerebellar tentorium, Cerebellar vermis, Deep cerebellar nuclei, Dentate nucleus

CerebellumCerebellum (small(small )brain)

44thth VentricleVentricle CNSCNS divisionsdivisions BrainstemBrainstem divisionsdivisions

Midbrain Mesencephalon

Pons

Medulla BasicBasic anatomicalanatomical datadata ofof cerebellumcerebellum

 Weight ~130 g (10% of the total brain volume)  Location -  Separated from the by the  Cerebellum/ = 1/8 (adult); 1/20 () MajorMajor componentscomponents ofof cerebellumcerebellum

 CortexCortex  DeepDeep nucleinuclei  WhiteWhite mattermatter  deepdeep WMWM  cerebellarcerebellar pedunclespeduncles MajorMajor componentscomponents ofof cerebellumcerebellum OrganizationOrganization ofof cerebellarcerebellar cortexcortex

 Folia (folds, equivalent to gyri of )  Lobules (groups of folia)  Lobes (groups of lobes)

The branching pattern of the into the cerebellar convolutions inspired early anatomists to refer to it as the (Latin, tree of life); hence, the name folia (Latin, leaves) rather than gyri is used to describe the convolutions.

Folia ↓ Lobules ↓ Lobes CerebellarCerebellar cortexcortex consistsconsists ofof vermisvermis andand hemisphereshemispheres

crus cerebri aqueduct

Cerebellar hemisphere Vermis VermisVermis andand hemisphereshemispheres areare divideddivided intointo lobeslobes byby fissuresfissures

Lobulus semilunaris sup.

Posterolateral fissure VentralVentral viewview ofof cerebellumcerebellum

4th ventricle

(=Inferior cerebellar notch) Vermis Hemisphere Anterior Lobe Lingula ------Centralis Ala lobuli centralis fissura prima Lob. quadrangularis ant. Declive Lob. quadrangularis post. horizontal fissure Folium Lob. semilunaris sup. Posterior Lobe Tuber Lob. semilun. inf./gracilis Pyrami s Lob. biventer posterolateral fissure Uvula Tonsilla Nodul us LobulesLobules ofof vermisvermis

Lingula Centralis C Culmen C Declive D Folium F Tuber T Pyramis P Uvula U Nodulus CerebellumCerebellum –– selectedselected lobuleslobules

Basis pontis

Tegmentum pontis F F CerebellumCerebellum –– selectedselected lobuleslobules

Cerebellar Tonsil CerebellumCerebellum –– selectedselected lobuleslobules && WMWM

SCP

MCP ICP

Flocculus Nodulus DeepDeep cerebellarcerebellar nucleinuclei -- DEFGDEFG

fastigial globose emboliform dentate DeepDeep cerebellarcerebellar nucleinuclei (DEGF)(DEGF) Nodulus Fastigial

Dentate nucleus

Globus and Globose Emboliform nucleus nuclei together Emboliform are known as: nucleus DeepDeep cerebellarcerebellar nucleinuclei

Dentate Nucleus OriginOrigin ofof CNSCNS subdivisionssubdivisions TheThe cerebellumcerebellum developsdevelops fromfrom thethe metencephalicmetencephalic vesiclevesicle

Neural tube folding (5 th -8th wk) AlarAlar vs.vs. BasalBasal plateplate derivativesderivatives -- ponspons

 somatic are alar plate Alar plate = afferent = sensory  visceral precursors migrated Basal plate = efferent = motor  visceral ventrally  somatic

The basal plate → primarily efferent nuclei (CN V, VI, VII, superior salivatory nuclei) The alar plate → somatic and visceral sensory nuclei (CN V, VIII, pontine nuclei) The cerebellum is derived from the of the alar plate

saggital section - lateral view dorsal view The cerebellum is derived from the rhombic lip of the alar plate

Rhombic lip Primordium cerebellar cortex

Alar plate Basal plate

Sulcus Pontine nuclei saggital section - lateral view cross-section limitans

 ~ 5th week of development → the lateral parts of the alar plates on both sides of the roof of metencephalon join to form the rhombic lips, which eventually become the and hemispheres  The remaining part of the alar plate forms the superior and inferior medullary veli BasicBasic stepssteps ofof cerebellarcerebellar histogenesishistogenesis

 Characterization of the cerebellar territory the  Formation of two compartments of cell proliferation → GABAergic & Glu-ergic  Inward migration of the precursors  Differentiation of cerebellar neurons EstimatedEstimated timetime ofof developmentdevelopment ofof variousvarious brainbrain regiregionsons

Modified from Bayer SA et al. Neurotoxicology 14:83–144, 1993 TheThe brainstembrainstem isis connectedconnected toto thethe cerebellumcerebellum viavia thethe cerebellarcerebellar pedunclespeduncles

superior (SCP) Brachium conjunctivum MidbrainMidbrain ↔↔ CerebellumCerebellum SCP is the principal output path of the cerebellum (it has also a little input)

middle cerebellar peduncle (MCP) Brachium pontis PonsPons →→ CerebellumCerebellum MCP is the principal input path of the cerebellum (it has no output)

inferior cerebellar peduncle (ICP) Restiform body MedullaMedulla oblongataoblongata ↔↔ CerebellumCerebellum ICP has both inputs and outputs CerebellarCerebellar inputsinputs && outputsoutputs -- overviewoverview

INPUTS: OUTPUTS:

SCP: SCP: • VSCT • • VA/VL - from dentate and interpositius nuclei MCP: • Pontocerebellar tract - MCP: from pontine nuclei • none

ICP: ICP: • • P/M reticular formations- • Vestibular ganglion from and • DSCT - from Clarke’s flocculus/nodulus nucleus • Lateral vestibular nucleus- • - from flocculus/nodulus and from inferior olive (climbing fastigial nucleus fibers) MajorMajor cerebellarcerebellar inputsinputs

Middle cerebellar peduncle (decussation)

Inferior cerebellar peduncle (ipsilateral)

Purves, et al, , 3rd ed. Major cerebellar outputs

Deep Cerebellar Nuclei

Superior Cerebrocerebellum to Dentate Nucleus cerebellar peduncle Spinocerebellum to Interposed Nuclei (decussation) Vestibulocerebellum to Fastigial Nucleus CerebellarCerebellar functionalfunctional modulesmodules

 VestibulocerebellumVestibulocerebellum  SpinocerebellumSpinocerebellum  CerebrocerebellumCerebrocerebellum

Purves, et al, Neuroscience, 3rd ed. TheThe functionalfunctional regionsregions ofof thethe cerebellumcerebellum havehave differentdifferent inputsinputs andand outputsoutputs

Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. VestibulocerebellumVestibulocerebellum ((= archicerebellumarchicerebellum )) →→ brainbrain stemstem centerscenters forfor controllingcontrolling eyeeye andand headhead movementsmovements

otolith organs

 Inputs – otolith organs of , inner ear, vestibular nuclei fastigial nucleus  Outputs (via fastigial Vestibular nuclei nucleus) – vestibular nuclei (medial, inferior, and superior ) Medial vestibulospinal  Function – neck muscle & tract (descending MLF)

control Lateral  Clinical correlates – and disturbances in body equilibrium (truncal ) VestibulocerebellumVestibulocerebellum –– cerebellarcerebellar cortexcortex

Maintenance of equilibrium and coordination of eye movements

Origin: Flocculus or Nodulus Course: ICP, or direct to vestibular nucleus Termination: Vestibular Nuclei Laterality: Ipsilateral VestibulocerebellumVestibulocerebellum –– deepdeep nucleinuclei

Main efferent mechanism from vermis to influence vestibulospinal and reticulospinal tracts

Origin: Fastigial Nucleus Course: ICP Termination: Vestibular Nuclei Laterality: Bilateral VestibulocerebellumVestibulocerebellum –– outputoutput (ICP)(ICP)

ICP From Vestibular nuclei and Vestibular ganglion (Scarpa ’s), for balance and coordination

Origin: Flocculus or Nodulus Course: ICP, or direct to vestibular nucleus Termination: Vestibular Nuclei Laterality: Ipsilateral SpinoSpino cerebellumcerebellum ((= paleopaleo cerebellumcerebellum )) →→ laterallateral andand medialmedial motormotor systemssystems

 Lateral systems → limb muscles (fine movements); Medial systems → proximal (axial) (SCP) muscles  Inputs – (dorsal & ventral spinocerebellar tracts, DSCT/VSCT), accessory cuneate nucleus (cuneocerebellar tract (CCT)

 Outputs ICP Accessory cuneate nucleus (ACN)  Vermis - via fastigial nucleus → brain stem nuclei that give rise to reticulospinal and vestibulospinal tracts  Intermediate hemisphere - via interposed nuclei (EG) → red nucleus, thalamus (VL)  Function – quality control of movements  Vermis → , neck, and trunk  Intermediate hemisphere → limbs  Clinical correlates – muscle rigidity, ataxia, dysmetria SpinocerebellumSpinocerebellum DorsalDorsal SpinocerebellarSpinocerebellar TractTract

Clarke's nucleus transmits sensory information from the leg and lower trunk

Origin: Clarke’s nucleus, T1-L2 Course: Dorsolateral spinal cord and medulla, enters the cerebellum via ICP Termination: granule cells of the vermis and intermediate zone Laterality: Ipsilateral SpinocerebellumSpinocerebellum DorsalDorsal SpinocerebellarSpinocerebellar TractTract

Clarke's nucleus transmits sensory information from the leg and lower trunk

Origin: Clarke’s Column, T1-L2 Course: Dorsolateral spinal cord and medulla, enters the cerebellum thru ICP Termination: granule cells of the vermis and intermediate zone Laterality: Ipsilateral SpinocerebellumSpinocerebellum DorsalDorsal SpinocerebellarSpinocerebellar TractTract

ICP

Clarke's nucleus transmits sensory information from the leg and lower trunk

Origin: Clarke’s Column, T1-L2 Course: Dorsolateral spinal cord and medulla, enters the cerebellum thru ICP Termination: granule cells of the vermis and intermediate zone Laterality: Ipsilateral SpinocerebellumSpinocerebellum DorsalDorsal SpinocerebellarSpinocerebellar TractTract

Origin: Clarke’s Column, T1-L2 Course: Dorsolateral spinal cord and medulla, enters the cerebellum thru ICP Termination: granule cells of the vermis and intermediate zone Laterality: Ipsilateral Somatotopic maps of the body surface in the (spino)cerebellum

Vermis

Intermediate hemisphere

 Intermediate hemisphere → limb muscles  Vermis → axial muscles Purves et al, Neuroscience, 3rd ed. The hallmark of patients with cerebellar damage is difficulty producing smooth, well- coordinated movements. Instead, movements tend to be jerky and imprecise, a condition referred to as cerebellar ataxia.

Dysmetria Ataxia - drunken sailor CerebellarCerebellar a b c AtaxiaAtaxia

Ataxic and position: Left cerebellar tumor

a. Sways to the right in d standing position b. Steady on the right leg c. Unsteady on the left leg d. ataxic gait CerebroCerebro cerebellumcerebellum ((= neoneo cerebellumcerebellum )) →→ premotorpremotor andand associationassociation corticalcortical areasareas

 Inputs – pontine nuclei (via MCP)  Outputs (via dentate nucleus) – thalamus (VL) & red nucleus (parvocellular division)  Function – motor memory & learning, recently – higher brain functions, e.g. attention  Clinical correlates – neocerebellar symptoms are usually combined with paleocerebellar (e.g. , dysmetria, ataxia) CerebroCerebro cerebellumcerebellum LateralLateral hemispherehemisphere

Origin: Pontine Nuclei Course: Immediately decussates and enters MCP Termination: granule cells of the cerebellar hemispheres Laterality: Contralateral CerebroCerebro cerebellumcerebellum DentateDentate NucleusNucleus

Main efferent mechanism to cerebral cortex for motor planning & memory

Origin: Dentate nucleus Course: SCP, decussates ventral to IC Termination: Red Nucleus or VA/VL Nucleus of Thalamus Laterality: Contralateral CerebroCerebro cerebellumcerebellum -- inputinput PontocerebellarPontocerebellar TractTract

preprogram of fine motor movements, esp. upper extremity

Origin: Pontine Nuclei Course: Immediately decussates and enters MCP Termination: granule cells of the cerebellar hemispheres Laterality: Contralateral CerebroCerebro cerebellumcerebellum -- inputinput OlivocerebellarOlivocerebellar TractTract

Origin: Course: Decussates immediately to enter the ICP Termination: Purkinje cells of hemisphere Laterality: Contralateral CerebellumCerebellum andand motormotor learninglearning

 DeficitsDeficits inin learninglearning complexcomplex motormotor taskstasks afterafter cerebellarcerebellar lesionslesions  fMRIfMRI studiesstudies –– cerebellumcerebellum activeactive duringduring learninglearning ofof novelnovel movementsmovements  PostulatedPostulated thatthat cerebellarcerebellar nucleinuclei storestore certaincertain motormotor memoriesmemories  MayMay bebe involvedinvolved inin cognitivecognitive functionsfunctions SummarySummary ofof cerebellarcerebellar functionalfunctional modulesmodules

Vestibulo- Spino- Cerebro- cerebellum cerebellum cerebellum Cortex Flocculonodular Vermis, Intermediate Lateral hemisphere

Deep Fastigial Emboliform, Dentate Nuclei Globose Inputs Vestibular nuclei Spinal and Corticopontine/ paths pontocerebellar Outputs Vestibular nuclei; RF SCP to Red Nucleus; SCP to VA/VL Fastigial to RF

Function Eye movements; Body and limb Planning and balance movements executive of hand movements Vestibulocerebellum Spinocerebellum Cerebrocerebellum CerebellumCerebellum –– overviewoverview ofof functionsfunctions

 Cerebellar hemisphere Planning & execution of skilled movements  Intermediate zone Limb movement, intended vs. actual  Vermis Axial movement, intended vs. actual  Flocculonodular lobe Equillibrium, eye movement PathwaysPathways involvedinvolved inin motormotor controlcontrol

Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. CerebellarCerebellar microcircuitrymicrocircuitry

 EachEach foliumfolium –– cortexcortex andand deepdeep WMWM  33--LayeredLayered cortexcortex  molecular layer – parallel fibers from granule cells  layer – single cell thick  granule cell layer – granule cell bodies  DeepDeep whitewhite mattermatter –– projectionsprojections ofof PurkinjePurkinje cellcell fibersfibers toto deepdeep nucleinuclei CerebellarCerebellar cortexcortex

 MolecularMolecular layerlayer (under(under thethe pia)pia)  stellate cells – GABAergic  basket cells – GABAergic  Purkinje cell  non -myelinated from granule cell layer  PurkinjePurkinje cellcell layerlayer  Purkinje cells – GABAergic  Bergmann glia – -like cells  GranuleGranule cellcell layerlayer  granule & unipolar brush neurons – glutamamatergic  Golgi & Lugaro cells – GABAergic  cerebellar glomeruli CerebellarCerebellar cortexcortex -- histologyhistology

Purkinje cells

Molecular layer

Granule cell layer White matter

Purkinje cell layer CerebellarCerebellar cortexcortex (H&E)(H&E) CerebellarCerebellar cortexcortex (Golgi(Golgi stain)stain)

dendrites

nucleus

PC

 PM =  ML = molecular layer  GL = granule cell layer GolgiGolgi ’’ss cerebellumcerebellum

A gift to G. Retzius , 1886

Human cerebellum

CerebellarCerebellar cortexcortex –– cytoarchitecturecytoarchitecture (cytoarchitectonics)(cytoarchitectonics)

 Inhibitory neurons (GABA)  Golgi cells  Basket cells  Stellate cells  Purkinje cells  Other (e.g. Lugaro cells)  Excitatory neurons (Glu)  Granule cells  Other (e.g. unipolar brush cells) Kandel, Schwartz, Jessell; Principles of Neural Science, 4 th ed. PurkinjePurkinje cellcell layerlayer

 PurkinjePurkinje cellcell layerlayer →→ PurkinjePurkinje cellscells  massive, flat apical dendritic tree  basal  the sole output of the cerebellar cortex PurkinjePurkinje cellscells spanspan thethe entireentire cerebellarcerebellar cortexcortex

Molecular layer

Purkinje cell layer

Granule cell layer

White matter PurkinjePurkinje cellscells && granulegranule neuronsneurons

Purkinje

granule GranuleGranule neuronsneurons inin 3D3D

3D reconstruction of granule cells and their Brainbow mice axons (341 axons & 93 granule neurons) doi:10.1038/nature06293 AxisAxis ofof granulegranule cellcell axonsaxons isis perpendicularperpendicular toto thethe axisaxis ofof PurkinjePurkinje cellcell dendritesdendrites

The granule cells send their axons upward, into the molecular layer, where they bifurcate in a T- like manner to become the parallel fibers. The nonmyelinated parallel fibers run perpendicular through the Purkinje cell dendrites (like the wires running between telephone poles) and form excitatory synapses on these dendrites. SpecificSpecific proteinsproteins cancan bebe usedused asas markersmarkers ofof cerebellarcerebellar neuronalneuronal populationspopulations

Calbindin LugaroLugaro cellscells –– inhibitoryinhibitory interneuronsinterneurons

Purkinje

Purkinje

Golgi

Lugaro Lugaro

Journal of Neurocytology 32, 217–227 (2003) BergmannBergmann ’’ss glia//oligodendrocytesglia/astrocytes/oligodendrocytes

pia

molecular layer

Merged signal oligodendrocytes Bergmann/astrocyte BergmannBergmann gliaglia

Bergmann glia processes Purkinje cells

Granule cell layer Molecular layer BergmannBergmann gliaglia CerebellarCerebellar microcircuitrymicrocircuitry -- overviewoverview

Other cerebellar cells

Purkinje cell

Deep nuclei Afferent fibers

Inhibitory (GABA) Excitatory (Glu) Thalamus CerebellarCerebellar microcircuitrymicrocircuitry

 Inputs to cerebellum  Mossy fibers → granule cells  Climbing fibers → Purkinje cells  Massive parallel fiber input, from granule cells, onto extensive dendritic tree of Purkinje cells  Inhibitory modulate the excitation of Purkinje cells  Only Purkinje cells project out of cerebellar cortex – to parallel fiber

Climbing fiber input → input → diffuse highly specific and sharply and complex (1 mossy fiber focused on Purkinje cells (1:1) → many granule cells)

Mossy fibers – from all other Climbing fibers – from inputs (cortex, spinal cord, inferior olive vestibular & reticular nuclei)

granule cell

mossy fiber Basket & Stellate Golgi neurons inhibit neurons are located in the excitatory input of the molecular layer mossy fibers to granule and receive excitatory cells. This inhibitory inputs, primarily from S B mild inhibition synapse is made in the the parallel fibers (i.e. granular layer, in a granule neurons). strong complex structure These cells give rise to inhibition termed the cerebellar inhibitory synapses on glomerulus. Purkinje cells. Go The synapse is located on the Purkinje cell body → strong inhibition

The synapse is Glomerulus located on the Purkinje cell dendrites → mild inhibition TheThe cerebellarcerebellar glomerulusglomerulus

 PresynapticPresynaptic elementselements  mossy fiber terminal (rosette)  axon  PresynapticPresynaptic elementelement  granule cell  EnsheathingEnsheathing glialglial cellscells TheThe cerebellarcerebellar glomerulusglomerulus InteractionsInteractions ofof cerebellarcerebellar neuronsneurons -- overviewoverview MouseMouse cerebellarcerebellar mutantsmutants helphelp usus identifyidentify thethe importanceimportance ofof eacheach cellcell typetype

Purves, et al, Neuroscience, 3rd ed. PrinciplesPrinciples ofof cerebellarcerebellar histogenesishistogenesis

 MostMost ofof thethe cerebellumcerebellum developsdevelops fromfrom progenitorsprogenitors locatedlocated inin thethe rhombicrhombic lips,lips, specializedspecialized regionsregions ofof thethe alaralar plateplate ofof thethe dorsolateraldorsolateral metencephalonmetencephalon  MigrationMigration ofof developingdeveloping cerebellarcerebellar neuronsneurons isis extenextensive,sive, muchmuch moremore soso thanthan forfor brainbrain stemstem oror spinalspinal cordcord neurons.neurons.  InitiallyInitially thethe cerebellarcerebellar surfacesurface isis smooth,smooth, butbut latelaterr inin development,development, fissuresfissures formform thatthat areare orientedoriented fromfrom ononee sideside toto thethe otherother BasicBasic stepssteps ofof cerebellarcerebellar histogenesishistogenesis

 Characterization of the cerebellar territory the hindbrain  Formation of two compartments of cell proliferation → GABAergic & Glu-ergic neurons  Inward migration of the granule cell precursors  Differentiation of cerebellar neurons upper RL CerebellarCerebellar lower RL alar plate basal plate morphogenesismorphogenesis

 5-6 weeks → cerebellar primordium formed  12 th week → fissures begin to th alar plate 4 V upper RL form (posterolateral is the first fissure) ~6 weeks lower RL basal plate  Directions of progenitor cell migration to form major cerebellar types  Radial  Tangential → form the external granule cell layer (EGL) ~12-13 weeks GluGlu --ergicergic neuronsneurons areare derivedderived fromfrom thethe upperupper rhombicrhombic liplip (RL)(RL) ofof thethe alaralar plateplate →→ formform prenatallyprenatally EGLEGL

GABAergicGABAergic neuronsneurons areare derivedderived fromfrom thethe ventricularventricular zonezone (VZ)(VZ) ofof thethe neuralneural tubetube (alar(alar plateplate side)side) ModesModes ofof migrationmigration

EGL (external granule cell Glu-ergic  GABAergic layer) precursor  Glu -ergic precursors migration neurons migrate radially migrate non - along fibers of radially radial glia (type of (tangentially) early stem cells) Radial glia Rhombic lip AtAt birthbirth cerebellumcerebellum isis almostalmost smoothsmooth –– foliationfoliation takestakes placeplace postnatallypostnatally

Birth Adult DuringDuring latelate embryonicembryonic andand earlyearly postnatalpostnatal lifelife granulegranule cellcell precursorsprecursors migratemigrate fromfrom EGLEGL toto IGLIGL alongalong BergmannBergmann gliaglia fibersfibers

Cerebellar folia form as a result of granule cell migration (mostly postnatally) SummarySummary ofof cerebellarcerebellar histogenesishistogenesis

 VentricularVentricular zonezone →→ GABAergicGABAergic neuronsneurons  RhombicRhombic liplip →→ GluGlu -- ergicergic neuronsneurons  Sequence:Sequence:  PC & deep nuclei – from ~2 months  Golgi, basket, stellate  Granule neurons – from 5 th month to postanatally MedulloblastomaMedulloblastoma isis thethe mostmost commoncommon pediatricpediatric brainbrain tumortumor

Medulloblastomas arise from granule cell precursors BBloodlood supplysupply ofof thethe cerebellumcerebellum

Superior cerebellar (SCA)

Anterior inferior cerebellar artery (AICA)

Posterior inferior cerebellar artery (PICA) Superior cerebellar artery (SCA)

Anterior inferior cerebellar artery (AICA)

Posterior inferior cerebellar artery (PICA) ArteriesArteries ofof cerebellumcerebellum –– fromfrom basilarbasilar arteryartery

 PPosteriorosterior inferiorinferior cerebellarcerebellar arteryartery (PICA)(PICA)  most of the inferior surface of the cerebellum (cerebellar hemispheres, inferior vermis, and the tonsils )  of the 4th ventricle  AAnteriornterior inferiorinferior cerebellarcerebellar arteryartery (AICA)(AICA)  a small area of the anterolateral part of the inferior surface o f the cerebellum  if AICA is large , the ipsilateral PICA is usually hypoplastic  SSuperioruperior cerebellarcerebellar arteryartery (SCA)(SCA)  most of the superior surface of the cerebellar hemisphere and vermis  deep cerebellar nuclei DorsalDorsal surfacesurface ofof cerebellumcerebellum -- arterialarterial territoriesterritories VVentralentral surfacesurface ofof cerebellumcerebellum -- arterialarterial territoriesterritories

VenousVenous drainagedrainage ofof thethe cerebellumcerebellum TheThe 44 thth VentricleVentricle

 Anterior wall – fossa rhomboidea (floor)  Posterior wall (roof)  Beneath the cerebellum and above dorsal surfaces of the and MMajorajor structuresstructures seenseen inin thethe floorfloor ofof thethe 44thth ventricleventricle 44thth VentricleVentricle

Facial Colliculus

Hypoglossal Trigone

Vagal Trigone

What is there under these elevations? Cranial Nuclei TheThe 44 th ventricleventricle isis boundbound onon thethe sideside byby thethe cerebellarcerebellar peduclespeducles Foramen of Luschka & formation of stria medullaris

arcuatocerebellar fibers

Stria medullaris of 4 th ventricle

Foramen of Luschka MMajorajor structuresstructures seenseen inin thethe roofroof ofof thethe 44th ventricleventricle   Cerebellum  - ependyma ( inferior medullary velum) covered by pia mater

Superior velum Inferior velum SuperiorSuperior medullarmedullar velumvelum && CNCN IVIV

 The superior medullary velum contains the decussating fibers of the trochlear , a lesion of this area may produce bilateral palsy (superior medullary velum syndrome). The 4th ventricle communicates with the subarachnoid space through three foramina in its roof: 1 midline foramen (of Magendie) 2 lateral foramina (of Luschka)

Central canal ends blindly