Cerebellum PDF

Cerebellum 10 cerebralhemisphere pons midbrain cerebellum medullaoblongata spinalcord median view surface of cerebellumishighlyconvulated...

Cerebellum 10 cerebralhemisphere pons midbrain cerebellum medullaoblongata spinalcord median view surface of cerebellumishighlyconvulated Folia d folium  cerebellar peduncles nervefibresor pathwaysthattravelinor outofcerebellum Brainstem Superior cerebellar peduncle almost entirely an efferentpathway Deep cerebellarnuclei via Superiorcerebellar peduncle Thalamus superiorcolliculus midbrain controlmovement of head eye cortex primarymortor premotorcortex Middle cerebellar peduncle an afferentpathway most ofthe cellbodiesthatgiverisetothis pathway are pontine nuclei contralateralpons seen as grey matter scatteredacross basilar part of pons cortex sends projections via corticopontine fibres pontinenuclei sends fibres outas transverse pontine fibres travelsto levebellum contralaterally via middle cerebelar peduncle Inferior cerebellar peduncle most complicated one on rightandoneonleft contains bothafferentandefferentpathways Afferent pathway Efferentpathway Vestibularnuclei vestibularnuclei spinalcord reticularformation brainstem Lobes of the cerebellum anteriorlobe middle posterior lobe floccular lobe largestlost Most primitive Oldest Flocculonodular lobe vestibulecerebellum vestibularnucleiprojects to it Functional Regions of cerebellum recievesinfo fromspine aboutposition of body newest lateraltovermis Oldest  Archicerebellum vestibulocerebellum recievesinputfromvestibular nuclei maintainbalance equilibrium vestibulo ocularregulation Paleocerebellum Spinocerebellum muscletone andposture recieves proprioceptiveinfo from spinalcord medianzone vermis movementofproximal muscles eg headneck trunk paramedianzone intermediatezone movementofdistalmuscles e hands feet g Neocerebellum Cerebrocerebellum Welldevelopedinprimatesand particularlyprominentinhumans occupiesmostoflateralcerebellum recieves inputindirectlyfrom cerebralcortexviapontinenuclei a n n afffftitthmovement corticopontine fibres pontinenuclei MAN transverse pontine fibresthey crossmidline baseofpons middle cerebellar peduncle lateral parts of thecerebellarhemisphere cereberocerebellum a k a neocerebellum vestibulo ocular reflex mechanism which maintains theeyeson a visual target when head moves 020 QQ o y enables clear vision during head movements by producing compensatory eye movements simple form of motor learning adaptation structures of the cerebellum transverse view 3 layers in cerebral cortex molecular loutermost Purkinje cell Granular linner most  Molecular layer contains 2 cell types stellate cells basket cells contains more celltypesbutfocus on main stellate cells Basket cells star shaped synapse with Purkinje cells recievesinputfromparallelfibres and provides input to Purkinjecells Purkinje cell layer containsonlyPurkinje cells they're the onlyoutputcells of the cerebellar cortex sendsdendrite into the molecular layer recievesinput from parallelfibres and climbing fibres long axons synapse with cells of one of the intracerebellarnuclei  Granular layer contains granule cells and golgi cells Granule cells granularlayerdenselypackedgranulecells eachcell gives rise to 4 5 dendrites makeclawlike ending Synapse with mossy fibres granule cells axon travels into molecularlayer bifurcates T shapebranches create parallel fibres 4 which synapse w Purkinje cells I knownasparallelbecauseit liesparallelto surface of cerebellum folial Golgicells relievesinputfromthe parallelfibres provides inhibitory feedback to granule cells  Cerebellar cortex rememberonlyoutputcell is Purkinjecell in Purkinjelayer Cerebellar inputs AFFERENT PATHWAYS 2 main inputs 1 mossyfibres 2 Climbing fibres bothexcitatory but arise from diff sources  2 main inputfrom mossyfibres and climbingfibres singleclimbing fibre many climbing synapses mossy summarydiagram Intracerebellar nuclei a na deep cerebellar nuclei embedded inwhitematter 4 nuclei from lateral to medial Dentate nucleus largest crumpledbagshape associated w neocerebellum Emboliform nucleus songuspetonated Emboliform Globosenucleus Globose Fastigial Fastigialnucleus  Dentate Dentate nucleus Dates Neocerebellum location lateral parts of the cerebellar hemisphere cerebrocerebellum purkinjecells here send projections to dentate nucleus sends projection via 7 Superior cerebellar f peduncle crosses midline d decussation v cortex  cerebellar pathways inputs spinal cord brainstem cortex viabrainstem visual auditoryinputsprovideadditional sensory signals that supplement the proprioceptive inforegardingbodyposition motion cerebellar pathway outputs axons of the neurones that form thedeep cerebellarnuclei constitute the efferent outflow from the cerebellum Deep cerebellar nuclei Thalamus Red nucleus Vestibular Reticular complex formation cortex spinal cord  Functions of cerebellum influences regulates voluntarymovement controlsthe maintenance of balance posture muscle tone motor coordination involved in motorlearning andbehaviour Also monitorsmovements anddetects errors graduates harmonisesmuscletonemaintain normal bodyposture permitsvoluntarymovementto take place smoothly with PRECISION EFFICIENCY not able to initiatemusclemovement lesions of the cerebellum Intension tremor tremorshappeningduring movement involuntaryrythmicmuscle contractions Hyptonia decreasedmuscletone cerebellar ataxia ataxicgait staggering widebasedgait lackof voluntary coordinationofmusclemovement Dysarthia slowness ofspeech scannTng of speech spokenwordsare brokenupintosyllables separated bynoticeablepause Each cerebellar hemisphere is concerned with sameside of thebody ipsilateral sign symptoms right sideinjured brain rightside