CHAPTER XIII. 

 Telencephalon — Non-olfactory Portions. 



THE non-olfactory portions of the telencephalon comprise 

 the basal ganglia and the neopallium. The basal 

 ganglia, according to the usual classification, consist of 

 four centres, the caudate and lentiform nuclei, the amygdala, 

 and the claustrum, though the claustrum is really derived from 

 the pallium. The amygdala, moreover, is not really non- 

 olfactory, as we have already seen. The caudate and lenti- 

 form nuclei, with the white fibres passing between or through 

 them, make up the corpus striatum, in which the amygdala is 

 sometimes included. 



In the majority of mammals, including the human species, 

 the caudate and lentiform nuclei are separated by a thick mass 

 of myelinated fibres, the internal capsule, which is a direct 

 upward continuation of the pes pedunculi, and which is 

 composed chiefly of ascending and descending axpns between 

 the non-olfactory cerebral cortex and lower parts of the 

 brain (projection fibres). In the rat, however, as is found to 

 be the case in many other lower mammals, though usually in 

 a smaller degree, the internal capsule has a more primitive 

 form, being made up of small bundles of fibres scattered 

 through the gray matter, so that there is no sharp division 

 of the latter into two parts (Pis. XIX. -XXIII. ); As a matter 

 of fact, the internal capsule never extends far enough forward 

 to separate the two parts completely, and even in man, where 

 there is the greatest separation, the anterior end of the caudate 

 nucleus is continuous with that of the outer part (putamen) 

 of the lentiform nucleus. 



The division into caudate and lentiform nuclei {nucleus 



