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12c external and internal features of thalamus - Coggle Diagram
12c
external and internal features of thalamus
External Features
The dorsal thalamus
is a large ovoid structure placed immediately lateral to the third ventricle.
It has an anterior and a posterior end and four
surfaces viz. dorsal, ventral, medial and lateral.
Anterior end (or pole)
lies just behind the interventricular foramen.
Posterior end (or pole)
is expanded and is called pulvinar.
It lies just above and lateral to the superior colliculus.
Dorsal or superior surface
is convex and triangular in outline.
It forms the part of floor of the central part of lateral ventricle.
Ventral or inferior surface
is related to the hypothalamus anteriorly and to the ventral thalamus posteriorly.
Lateral surface
is related to the posterior limbs of
internal capsule.
Medial surface
forms the greater part of the lateral wall of third
ventricle and is lined by ependyma.
The medial surfaces of the two thalami are connected by a short bar of grey matter called the interthalamic adhesion.
Inferiorly, the medial surface is separated
from the hypothalamus by hypothalamic sulcus.
Internal Structure
Like other parts of
brain, the thalamus
consists of grey matter
(mainly) and white
matter.
White matter
is scarce n includes
Stratum zonale
a thin layer of white matter covering the superior
surface of thalamus.
External medullary lamina
is a thin layer of white matter covering the lateral surface of thalamus.
It consists of thalamocortical and corticothalamic fibres.
Internal medullary lamina
is a Y-shaped sheet of white matter placed vertically in the grey matter of thalamus.
It consists mainly of internuclear thalamic connections.
Grey matter
is divided into 3 masses of nuclei by the
Y- shaped internal medullary lamina:
Anterior part,
Lateral part and
Medial part.