DIENCEPHALONDIENCEPHALON

Prof. Dr. Selda ÖnderoğluProf. Dr. Selda Önderoğlu

DIENCEPHALONDIENCEPHALON Diencephalon is

the part of CNS located on both sides of 3rd ventricle. Extends ant.ly from interventricular foramen postly to cerebral aequaduct.

PARTS OF DIENCEPHALONPARTS OF DIENCEPHALON

Thalamus, Hypothalamus, EpithalamusSubthalamus

ThalamusThalamus part of part of

diencephalondiencephalon located deeply located deeply

in the cerebral in the cerebral hemisphereshemispheres

Shape: eggShape: egg Gray matterGray matter

ThalamusThalamusRelations:Ant.:Head of caudate nucl.+

genu of internal capsule

Ant. End forms the post. Border of interventricular foramen

Post.:Pulvinar of thalamus

Surfaces of thalamusSurfaces of thalamus

Medial surfaceLateral surfaceSuperior surfaceInferior surface

medial surface medial surface Forms the upper part of lateral

wall of 3rd ventricle

interthalamic mass (adhesion)

Lateral surfaceLateral surface

Posterior limb of internal capsule

Seperated from lentiform nucleus by internal capsule

Superior surfaceSuperior surface

Terminal Sulcus (superior

Thalamostriate vein and stria terminalis courses here)

inferior surfaceinferior surface Ant. Separated from

Hypothalamus by hypothalamic sulcus

post Tegmentum of

Mesencephalon

Internal structureInternal structure

Gray matter ( nueorn groups, nuclei) White matter ( internal and external

medullary lamina)

Internal Medullary Lamina and Internal Medullary Lamina and External Medullary Lamina External Medullary Lamina

Nuclei of ThalamusNuclei of Thalamus anterior medial Ventral

(VPM&VPL) dorsal Posterior(in

pulvinar) Median intralaminar reticular

Anterior nuclei Anterior nuclei

Located in the anterior tubercle of thalamus located ant.

thought to be related to memory

Ventral Nuclei of ThalamusVentral Nuclei of Thalamus

ventral anterior ventral lateral ventral post. Posteromedial Posterolateral Posteroinferior

Metathalamus Metathalamus

lateral geniculate body

medial Geniculate body

Medial Geniculate bodyMedial Geniculate body

Related to auditory pathways

by the Brachium of inf. Colliculus it is connected to lateral lemniscus ( afferent) and send stimuli to the auditory center in cerebral cortex ( 41-42 of Brodman areas) (efferent)

Lateral Geniculate bodyLateral Geniculate body

Relay nuclei related to visionAfferent fibers from retina

and c superior colliculusEfferent fibers to Brodmann 17

Functions of ThalamusFunctions of Thalamus Conveys impulses related to different sensations to cerebral

sensory center (cortex).

Fibers from cerebellum, basal ganglia, peripheral sensory organs fist go to thalamus modified there and then goes to cerebral cortex.

Sense of smell first goes to its center in cortex, then relays in thalamus.