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DIENCEPHALON. Prof. Dr. Selda Önderoğlu. DIENCEPHALON. 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 DIENCEPHALON. Thalamus, Hypothalamus, Epithalamus Subthalamus. Thalamus.
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DIENCEPHALON Prof. Dr. Selda Önderoğlu
DIENCEPHALON • 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 DIENCEPHALON • Thalamus, • Hypothalamus, • Epithalamus • Subthalamus
Thalamus • part of diencephalon • located deeply in the cerebral hemispheres • Shape: egg • Gray matter
Thalamus Relations: Ant.: Head of caudate nucl.+ genu of internal capsule Ant. End forms the post. Border of interventricular foramen Post.: Pulvinar of thalamus
Surfaces of thalamus Medial surface Lateral surface Superior surface Inferior surface
medial surface Forms the upper part of lateral wall of 3rd ventricle interthalamic mass (adhesion)
Lateral surface • Posterior limb of internal capsule • Seperated from lentiform nucleus by internal capsule
Superior surface • Terminal Sulcus (superior Thalamostriate vein and stria terminalis courses here)
inferior surface • Ant. • Separated from Hypothalamus by hypothalamic sulcus • post • Tegmentum of Mesencephalon
Internal structure Gray matter ( nueorn groups, nuclei) White matter ( internal and external medullary lamina)
Nuclei of Thalamus • anterior • medial • Ventral (VPM&VPL) • dorsal • Posterior(in pulvinar) • Median • intralaminar • reticular
Anterior nuclei Located in the anterior tubercle of thalamus located ant. thought to be related to memory
Ventral Nuclei of Thalamus ventral anterior ventral lateral ventral post. Posteromedial Posterolateral Posteroinferior
Metathalamus medial Geniculate body lateral geniculate body
Medial 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 body Relay nuclei related to vision Afferent fibers from retina and c superior colliculus Efferent fibers to Brodmann 17
Functions 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.