头晕相关的脑解剖(小脑)

头晕相关的脑解剖CerebellumAnatomyRelevanttoDizzinessTimothyC.Hain,MDMarcelloCherchi,M.D.,Ph.D.Pagelastmodified:June14,2009Thispageismeanttoprovideageneraloutlineofcerebellarfunction.ItisadaptedfromaclinicalneuroanatomylecturegivenonayearlybasistoNorthwesternPTstudents.Thispageisunderconstructionandshouldnotbereliedupon.Thecerebellumwithsurroundingskullandspinalfluidoccupiesthebottom1/3ofthisaxialMRIimage.Whatisthecerebellumandwhatdoesitdo?Thecerebellumispartofthebrain.Itliesunderthecerebrum,towardstheback,behindthebrainstemandabovethebrainstem.Thecerebellumislargelyinvolvedincoordination.Personswhosecerebellumdoesn'tworkwellaregenerallyclumsyandunsteady.Theymaylookliketheyaredrunkevenwhentheyarenot.GrossAnatomy:CerebellarHemispheresandVermisCerebellarhemispheres,eachcontainingalateralandanintermediateportionVermis,situatedbetweenthetwocerebellarhemispheres;isbasicallycircular(interruptedbyfourthventricleventrally)GrossAnatomy:Lobes&LobulesAnteriorlobe:o1.Lingulao2.Centrallobuleo3.CulmenPosteriorlobe:o4.Decliveo5.Foliumo6.Tubero7.Pyramiso8.Uvulao9.TonsilFlocculonodularlobe:o(10.)Flocculus&nodulusGrossAnatomy:FissuresPrimaryfissure:separatesanteriorandposteriorlobesHorizontalfissure:separatesposteriorlobe’srostrallobules(declive,folium)fromitscaudallobules(tuber,pyramis,uvula,tonsil)Posterolateralfissure:separatesposteriorandflocculonodularlobesConnectionswithbrainstem:SuperiorcerebellarpeduncleconnectstomidbrainMiddlecerebellarpeduncleconnectstoponsInferiorcerebellarpeduncleconnectstomedullaSectionsoftheCerebellumVestibulocerebellumorarchicerebellumComprisestheflocculonodularlobeExtensiveconnectionswiththevestibularsystemPhylogeneticallyoldestSpinocerebellumorpaleocerebellumComprisesthevermis(medial)¶vermal(intermediate)regionExtensiveconnectionswiththespinalcord&brainstemPhylogeneticallyofintermediateageCerebrocerebellumorneocerebellumCompriseslateralportionsofcerebellarhemispheres(excludingparavermalregions)ExtensiveconnectionswithcerebralcortexthroughrelaystationsincerebellarnucleianddorsalthalamusPhylogeneticallyyoungestCEREBELLARPEDUNCLESSuperiorcerebellarpeduncle(brachiumconjunctivum)ConnectstomidbrainAfferents:onlyventralspinocerebellartractEfferents:MostoftheefferentsfromthecerebellumAlloftheefferentsfromthree(outoffour)pairsofnuclei:dentate,emboliform,andgloboseMiddlecerebellarpeduncle(brachiumpontis)ConnectstoponsAfferents:fromcerebralcortex(“corticoponto-cerebellarsystem”).Corticopontineprojections(originatinginthecerebralcortex)synapseinipsilateralbasalpons.Fromthere,mostpontocerebellarprojectionsdecussate,passthroughmiddlecerebellarpeduncleandentercerebellum.Asmallnumberremainipsilateral.Efferents:none.Inferiorcerebellarpeduncle(“corpusrestiform”or“restiformbody”)ConnectstomedullaTwocomponents:RestiformbodyoAfferents:Ascendingspinalproprioceptivefibersfromthreeofthespinocerebellartracts(dorsal,rostral,andcuneocerebellar)Ascendingfibersfromcontralateralinferiorolivarynucleitocerebellarcortex(olivocerebellarprojections)Reciprocalconnectionswithmotorreticularformationandspinocerebellum(paleocerebellum):reticulocerebellarandcerebelloreticularprojectionsJuxtarestiformbodyoMostlycontainsreciprocalconnectionstoandfromvestibulocerebellum(archicerebellum)andvermalportionofspinocerebellum(paleocerebellum):vestibulocerebellarandcerebellovestibularfibersCerebellarNucleiFastigialnucleusLocation:Roofofthe4thventriclePhylogeneticallyoldestAssociatedwiththevestibulocerebellum(archicerebellum)Afferents:oVestibulocerebellumoVermisEfferents:oViainferiorcerebellarpeduncleoTothevestibularnucleioSomeprojectdirectlytotheipsilateralsideoSomedecussate,looparoundsuperiorcerebellarpeduncleandreachthevestibularandreticularformationviatheuncinatebundleofRussellFunction:ControlsantigravitymusclesControlsproximalmusclesofstance(station)&walking(ambulation)Globoseandemboliform(the“interposednuclei”)Location:Roofofthe4thventricle,slightlylateraltothefastigialnucleiAfferents:Paravermianregionofspinocerebellum(paleocerbellum)Efferents:ViasuperiorcerebellarpeduncletocontralateralrednucleusFunction:oMainlyinvolvedinmodulationofstretchreflexesDistalmusclesDentatenucleusLocation:DeepwithincerebellarwhitematterLargestcerebellarnucleiAfferents:oPurkinjecellsofentirecerebrocerebellum(neocerebellum)andpartofspinocerebellum(paleocerebellum)oPremotor&supplementarymotorcorticesviapontocerbellarsystemEfferents:oThroughsuperiorcerebellarpeduncle;crosstocontralateralrednucleus&thenonventrolateralnucleusofthalamusFunction:oHelpstoinitiateandcontrolvolitionalmovementsVestibularnucleus“Displaced”cerebellarnucleiCloselyassociatedwithvestibulocerebellum(archicerebellum)Function:MaintaingazefixationMaintainuprightpostureCEREBELLARHistology:CorticalLayersMolecularlayer(outermostlayer)contains:oCellbodies:stellatecells,basketcellsoCellprocesses:dendritesofthePurkinjecells,dendritesofGolgicells,axons(parallelfibers)ofgranulecells,axonsofstellatecellsoPurkinjelayer(middlelayer)contains:oCellbodies:o