The Corpus Stratium

The Corpus StratiumThe corpus stratium owes its name to the striated appearance caused by the intermingling of numerous white fibres with the grey matter. It consists of two large nuclei which are completely seperated from one another in the greater part of their extent, but are joined together below at their anterior ends.

The inner of the two nuclei is in contact with the anterior extremity of the thalamus and projects into the cavity of the lateral ventricle (Fig. 61); it is called the caudate nucleus.

The outer nucleus is embedded in the white matter of the hemisphere and is termed the lenticular nucleus (Fig. 64).

In horizontal sections the lenticular nucleus is somewhat like a biconvex lens in shape; its internal surface is very sharply convex, the outer much less so. A flattened band of white fibres - the internal capsule - separates the internal surface from the caudate nucleus in front and from the thalamus behind.

This band is sharply curved, like the surface of the lenticular nucleus with which it is in contact; the bend is known as the genu of the internal capsule, and the other portions are termed respectively the anterior and posterior limbs.

In the white matter between the lenticular nucleus and the island of Reil is a thin vertical plate of grey matter - the claustrum.

The cells of the corpus striatum are principally of the multipolar type. They are connected by fibres to the thalamus and to the posterior parts of the brain. A striking fact is that very few fibres pass between the cerebral cortex and the corpus striatum.