ANATOMY AND PHYSIOLOGY OF NERVOUS SYSTEM. 



651 



situated in front of and slightly outward from the optic thalami. 

 The outer surfaces of the corpora are in relation with the island of 

 Reil and the centrum ovale of the hemispheres. Internally, they 

 are in apposition with the optic thalami and the gray layer of the 

 third ventricle. They are formed of two large nuclei: the caudate 

 and lenticular. 



The nucleus caudatus is so named from its resemblance to a pear 

 in shape. It lies inside the lateral ventricle upon its floor. The 



jorni* 



pineal tM 

 post, comnt* 

 .pineal body 



rostru 



ant. comm. 



lam. cin 

 opt. com m 



turula 



Fig. 258. Median Section of the Brain. 



titl.ualv. 

 pyramid 

 (QUAIN.) 



cells of this nucleus are of two types sensory and motor; the cells 

 of the motor type seem to be more abundant. 



The nucleus lenticularis, a part of the corpus striatum, is sepa- 

 rated from the caudate nucleus by the internal capsule. By reason 

 of its situation near the center of the body of the hemisphere and 

 outside of the ventricle it is called the extraventricular nucleus of 

 the corpus striatum. 



The lenticular nucleus is divided into three segments by two 

 layers of white matter placed within its thickness. The segments 

 are distinguished from one another by their color, which is most 

 pronounced in the external segment. The latter has received the 



