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).Relaytothespecificsensoryareaofthecerebralcortex;itisalsotheregulationcenteroftheautonomicnerveandendocrineunderthecerebralcortex.Therefore,whenthediencephalonisdamaged,sensorydisturbancesandspontaneoushyperesthesiaoccur,especiallypainfulhypersensitivity,andautonomicandendocrinedisorders,suchasbodytemperature,watermetabolism,sleep,moodandotherabnormalphenomena.