1. DIENCEPHALON Prof. Dr. Selda Önderoğlu

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

3. PARTS OF DIENCEPHALON Thalamus, Hypothalamus, Epithalamus Subthalamus

4. Thalamus part of diencephalon part of diencephalon located deeply in the cerebral hemispheres located deeply in the cerebral hemispheres Shape: egg Shape: egg Gray matter Gray matter

5. Thalamus Relations: Ant.: Head of caudate nucl.+ genu of internal capsule Ant. End forms the post. Border of interventricular foramen Post.: Pulvinar of thalamus

7. Surfaces of thalamus Medial surface Lateral surface Superior surface Inferior surface

8. medial surface Forms the upper part of lateral wall of 3rd ventricle interthalamic mass (adhesion)

9. Lateral surface Lateral surface Posterior limb of internal capsule Seperated from lentiform nucleus by internal capsule

10. Superior surface Terminal Sulcus (superior Thalamostriate vein and stria terminalis courses here)

13. inferior surface Ant. Separated from Hypothalamus by hypothalamic sulcus post Tegmentum of Mesencephalon

14. Internal structure Gray matter ( nueorn groups, nuclei) White matter ( internal and external medullary lamina)

15. Internal Medullary Lamina and External Medullary Lamina

16. Nuclei of Thalamus anterior medial Ventral (VPM&VPL) dorsal Posterior(in pulvinar) Median intralaminar reticular

17. Anterior nuclei Located in the anterior tubercle of thalamus located ant. thought to be related to memory

18. Ventral Nuclei of Thalamus ventral anterior ventral lateral ventral post. Posteromedial Posterolateral Posteroinferior

19. Metathalamus lateral geniculate body medial Geniculate body

20. 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)

21. Lateral Geniculate body Lateral Geniculate body Relay nuclei related to vision Afferent fibers from retina and c superior colliculus Efferent fibers to Brodmann 17

22. 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.