THE NERVOUS SYSTEM 



141 1 



the nucleus caudatus. The extravovtricular portion is embedded in 

 the white matter of the cerebral hemisphere, and is termed the 

 nucleus lenticularis. Between these two nuclei there is a part of 

 the thick tract of white fibres which constitutes the internal cap- 

 sule ; and on the outer side of the nucleus lenticularis there is the 

 thin lamina of white matter, called the external capsule. When a 

 coronal section is made through the corpus striatiun on a level 

 with the anterior part of the nucleus lenticularis, the white matter 

 of the front part of the internal capsule is seen to be intersected by 

 striae of grey matter which pass between the nucleus caudatus and 

 nucleus lenticularis. From the striped appearance thus produced 

 the body has received the name of corpus striatum. 



The nucleus caudatus is pyriform. The large round end is directed 

 forwards, and projects into the anterior comu of the lateral ventricle. 



Entrance to Descending 



Comu of Lateral 



Ventricle 



Hippocampus Major 



Fig. 595 . — Horizontal Section of the Brain through the Genu 



AND SpLENIUM of THE CORPUS CaLLOSUM (DaLTON). 



The narrow portion is directed outwards and baclavards in the 

 floor of the body of the lateral ventricle, where it lies on the outer 

 side of the optic thalamus, from which it is separated by the taenia 

 semicircularis. Its tapering tail is continued into the roof of the 

 descending comu of the lateral ventricle, and is prolonged in the 

 roof as far as the amygdaloid nucleus, in which it terminates. The 



