Diencephalon

Anatomicalfeatures

Thestructureismorecomplex,dividedintotheupperthalamus,dorsalthalamus,posteriorthalamus,subthalamusandhypothalamus.

(1)Themainstructureoftheepithalamusisthepinealgland,whichisanendocrinegland.

(2)Thedorsalthalamusiscomposedoftwoovalgraymattermasses,oneoneachside.Eachovalgraymattermassisdividedintoanteriorthalamicnucleus,medialthalamicnucleusandlateralthalamicnucleus.Theprethalamicnucleushasfunctionsrelatedtovisceralactivity.Themedialthalamicnucleusmaybetheintegratedcenterofsomatosensoryimpulsesandthelateralthalamicnucleusisthefinalrelaystationofthesomatosensorypathway.Ittransmitsskinsensoryandproprioceptiveimpulsestothecerebralcortex.Backtothecenter.

(3)Theposteriorthalamusincludesthemedialgeniculatebodyandthelateralgeniculatebody.Thereisthemedialgeniculatenucleusinthemedialgeniculatebody,whichisthelastrelaystationintheauditoryconductionpathway.Itreceivestheincomingauditoryfibersandsendsthefiberstotheauditorycenterofthecerebralcortex.Thereisthelateralgeniculatenucleusinthelateralgeniculatenucleus,whichisthelastrelaystationinthevisualconductionpathway.Itacceptstheincomingopticalfibersandsendsthefiberstothevisualcenterofthecerebralcortex.

(4)Thesubthalamusisthetransitionalareabetweenthemidbrainanddiencephalon.

(5)Thehypothalamusisthesubcorticalcenteroftheautonomicnerves,whichinteractswiththesecretionofcertainhormones,emotionalresponse,regulationofcertainmetabolisms(suchaswater,salt,sugar,fat,etc.),andbodytemperature,Cardiovascularmovement,theregulationofbreathingmovement,andtheregulationofappetite,sleep,awakening,biologicalclock(orcircadianrhythm),etc.areallrelated.Manyphysiologicalandpsychologicalstudiesinvolvethediencephalon,especiallythehypothalamus.

Thediencephalonandthetelencephalonbothderivefromtheforebrainwingplateintheearlyembryonicstage.Thediencephalonislocatedinthebackcenteroftheforebrain,andthetelencephalondevelopsintotheleftandrightcerebralhemispheres.Duetothehighexpansionofthetelencephalon,thediencephalonissurroundedbytheleftandrightcerebralhemispheresexceptforthepartthatbelongstothehypothalamusontheventralside,whichisexposedonthesurfaceofthebrain.Inthemid-sagittalsectionofthebrain,thelinefromtheposteriorcommissuretotheposterioredgeofthepapillarybodyrepresentsthejunctionbetweenthediencephalonandthemidbrain,andthelinefromtheinterventricularforamentotheopticchiasmrepresentsthejunctionbetweenthediencephalonandthetelencephalon.Theventricularcavityofthediencephaloniscalledthethirdventricle.

Theinnersideofthediencephalononbothsidesformsthesidewallofthethirdventricle.Atthejunctionofthemedialanddorsalside,thereisaraisedfiberbundle—thalamicmedullastriatum,whichisattachedtothethirdventriclechoroidtissue.Themedullaryveinsofthethalamusconnectthereintriangleback,andthereisareincommissureconnectionbetweentheleftandrightreintriangles,andthereisapinealglandbehindthiscommissure.Approximatelyinthemiddleofthethirdventriclewall,thereisanadhesive(orcentralmass)betweenthethalamusconnectingtheleftandrightventricularwalls.Ithasahypothalamicsulcusonitsventralside,fromthemidbrainaqueducttotheinterventricularforamen.Thestructurebelongingtothehypothalamussurroundsthefloorofthethirdventricle,andfromfronttobacktherearetheopticchiasm,thefunnel,thegraynodulesandthenipplebodyconnectingtheendplates.Onthebackofthediencephalon,bothsidesofthethirdventricleareheldbyovalgraymattermassesbelongingtothedorsalthalamus,withaprotrudinganteriorthalamicnoduleatthefrontendandanenlargedoccipitalattheback.Thereisthecaudatenucleusbelongingtothetelencephalonontheoutersideoftheback,andthestriaterminalisbetweenitandthediencephalon.Onthelowerandoutersideofthepillow,therearemedialgeniculatebodyandlateralgeniculatebody.Thelateralsurfaceofthediencephalonisfusedwiththeinternalcapsuleofthetelencephalon.Theventralsurfaceofthediencephalonisthepartexposedontheoutersurfaceofthebrain,withtheopticchiasmandoptictractbeforeit.Thefunnel,pituitaryandgraynodulesareinthemiddle,andthepapillarybodiesarepairedandlocatedbehindthegraynodules.

Diencephalondamage

Eachpartofthediencephalonhasitsownspecialfunction,butthemainfunctionistheacceptanceandinitialintegrationofimpulsesforsomaticandvisceralsensations(exceptsmell).Relaytothespecificsensoryareaof​​thecerebralcortex;itisalsotheregulationcenteroftheautonomicnerveandendocrineunderthecerebralcortex.Therefore,whenthediencephalonisdamaged,sensorydisturbancesandspontaneoushyperesthesiaoccur,especiallypainfulhypersensitivity,andautonomicandendocrinedisorders,suchasbodytemperature,watermetabolism,sleep,moodandotherabnormalphenomena.

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