THE TELENCEPHALON. 



1173 



The Internal Capsule. — Repeated mention has been made of the important 

 tract of white matter bearing the name of internal capsule (capsula interna) ; its 

 description, therefore, may be appropriately undertaken at this place. It is a broad, 

 compact band, of nerve-fibres which passes between the three large basal ganglia, 

 namely, the caudate and the lenticular nuclei and the thalamus. Although the details 

 of the internal capsule vary with differences both of direction and of position of the 



Thalamus 



Fornix 

 crus 



Spleniuni 

 of corpus 

 callosum 



Corpus calloBum 



Calcarine fissure 



Thalamus 



Retro-len- 

 ticular part 

 of internal 

 capsule 



Fornix 



Choroid 

 plexus in 

 inferior 

 horn of 

 lateral 

 ventricle 



Horizontal sections of brain, A at higher level than B, which passes through lower part of corpus striatum where 

 caudate and lenticular nuclei are continuous; relations of limbs of internal capsule to internal nuclei seen on right side. 



planes of section, its general relation to these three masses of gray matter is con- 

 stant, the caudate nucleus and the thalamus always lying to its inner side and the 

 lenticular nucleus to its outer aspect. When exposed by frontal sections passing 

 through the anterior part of the lateral ventricles (Fig. loio), the internal capsule 

 appears as a broad, oblique stripe, extending from above downward and inward, 

 bounded by the large caudate nucleus mesially, the lenticular nucleus laterally, 

 and below by the gray substance establishing continuity between the two nuclei. 



