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DIENCEPHALON

CEREBRUM Largest part of the

brain Situated in the

anterior and middle cranial fossa

Divided into two parts:

1. Telencephalon2. Diencephalon

DiencephalonDiencephalon

Sits on top of the brain stem Enclosed by the cerebral

hemispheres Made of four parts:

Thalamus Hypothalamus Epithalamus Subthalamus

DiencephalonDiencephalon

Consists of the 3rd ventricle and the structures that form its boundaries, most rostral part of the brainstem.

Ant.: Intervent. fora. Post.: where the 3rd

vent. Forms the cerebral aqueduct.

CHARACTERISTICS OF THE MIDBRAIN-DIENCEPHALIC JUNCTION

Addition of several masses of neurons surrounding the rostral part of the post. and lat. Mesencephalon.

Medial and lateral geniculate body fiber. Cerebral aqueduct expands into 3rd vent. Sup. Colliculi replaced by pre-tectal region Fasc. Retroflexor – vertical fibers traversing

the medial portion of the red nucleus.

Inferior surface of the Diencephalon Only exposed area to

the surface in the intact brain.

Hypothalamus and other structures:

Optic chiasma Infundibulum with the

tuber cinerium Mamillary body

Superior surface of the Diencephalon Concealed by the

fornix : thick bundle of nerve fibers from the hippocampus of temp. lobe and arches posteriorly over the thalamus to join the mamillary body

Roof of 3rd vent.

Lateral surface of the Dierncephalon

Bounded by the internal capsule

Medial surface of the Diencephalon Superior part by the

medial surface of the thalamus

Inferior part by the hypothalamus

These 2 areas are separated by a shallow sulcus the Hypothalamic sulcus.

Diencephalon

Diencephalon

Diencephalon

Diencephalon: Thalamus “Gateway to cerebral cortex” Most sensory stimuli project

to the thalamus, which in turn projects to the cerebrum.

Thalamus also influences moods and activities associated with strong emotion.

(Two concepts: Sensory integration and Mood)

Diencephalon:Thalamus Large ovoid mass of

gray matter forming a greater part of the Diencephalon.

Cell station to all main sensory system except the olfactory pathway.

Diencephalon

HYPOTHALAMUS

HYPOTHALAMUS

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