Medical brain notes 24

  The Thalamus (Dorsal Thalamus)          The thalamus (or dorsal thalamus) is a large mass of grey matter that lies immediately lateral to the third ventricle. It has two ends (or poles), anterior and posterior; and four surfaces, superior, inferior, medial and lateral.          The  anterior end (or pole)  lies just behind the interventricular foramen (Fig. 8.6). The  posteriorend (or pole)  is called the pulvinar. It lies just above and lateral to the superior colliculus. Thepulvinar is separated from the geniculate bodies by the superior brachium quadrigeminum.             The  medial surface  forms the greater part of the lateral wall of the third ventricle, and is lined by ependyma. The medial surfaces of the two thalami are usually interconnected by a mass of grey matter called the  interthalamic adhesion (c...

  Internal Structure of the Thalamus          The thalamus consists mainly of grey matter. Its superior surface is covered by a thin layer of white matter called the  stratum zonale;  and its lateral surface by a similar layer called the  externalmedullary lamina.          The grey matter of the thalamus is subdivided into three main parts by a Y - shaped sheet of white matter which is called the  internal medullary lamina  (Fig. 13.3). This lamina is placed vertically. It divides the thalamus into a lateral part, a medial part, and an anterior part situated between the two limbs of the ‘Y’ .          A number of nuclei can be distinguished within each of these parts. Only the more important of these are listed below (a)         Nuclei in the anterior part a.        ...