THE CEREBROS FINAL NERVOUS SYSTEM. 



52t 



The relations of the inter 



the lenticular nucleus externally (Fig. 3GO). 

 nal capsule are most important. 



Corpora Striata. (1. ) The corpora striata are situated in front of 

 the optic thalami, partly within and partly without the lateral ventricle. 

 Each corpus striatum consists of two parts. 



(a.) An mtra-ventricular portion (caudate nucleus) which is conical 

 in shape, with the base of the cone forwards; it consists of gray matter, 

 with white substance in its centre, (b. ) An extra-ventricular portion 

 (lenticular nucleus), which is separated from the other portion by a 

 layer of white material, which forms a portion of the internal capsule, _ 

 the anterior limb. The lenticular nucleus is seen, on a horizontal sec- 

 tion of the hemisphere, to consist of three parts, separated from one 

 another by white matter, of which the smallest is inside, each part some- 

 what resembling in shape a wedge. The upper and internal surface is- 

 in relation with the caudate nucleus, being separated from it by the ante- 



FIG. 361. Vertical section through the cerebrum and basic ganglia to show the relations of the 

 latter, co, cerebral convolutions; c.e., corpus cailosum; v.L, lateral ventricle; /, fornix; vIIL, third 

 ventricle; n.c., caudate nucleus; th, optic thalamus; n.l. } lenticular nucleus; c.t., internal capsule; 

 cl., claustrum; c.e., external capsule; m, corpus mammillare; t.o., optic tract; s.t.t, stria terrai- 

 nalis; n.a., nucleus amygdalse; cm, soft commissure. (Schwalbe.) 



rior limb of the internal capsule. The remainder of the internal surface is 

 in relation to the optic thalamus, being separated from it by theposterior 

 limb of the internal capsule. The anterior and posterior limbs of the 

 internal capsule meet at an acute angle, which is known as the knee of 

 the internal capsule. The horizontal section is wider in the centre 

 than at the end. On the outside is the gray lamina (claustrum) sepa- 

 rated by a thin white layer external capsule from the lenticular 

 nucleus. 



Optic Thalami. (2.) The Optic Thalami are oval in shape, and 

 rest upon the crura cerebri. The upper surface of each thalamus is 

 free, and of white substance, it projects into the lateral ventricle. The 

 posterior surface is also white. The inner sides of the two optic thalami 

 are in partial contact, and are composed of gray material uncovered by 

 white, and are, as a rule, connected together by a transverse portion. 



