/'///; r 



857 



pass from one to the other through the internal capsule, especially its anterior part. 

 Also each nucleus i-ont rihutes iiiiinerous (Hires to. and receives film's from, the in- 

 ternal capsule. These bundles of fibres both arising and terminating within the 

 nuclei, together with the grey substance among the fibres of the capsule, produce the 

 ribbed and striped appearance surest ing the name, corpus striatum. The caudate 

 nucleus the intra-ventricular part of the corpus striatum lies with its thicker 

 anterior part (head) closely relate 1 to the internal capsule, but its tail passes back- 

 wards around the posterior border of the capsule and curves downwards and forwards 

 into t he roof of the inferior cornu of the lateral ventricle. 



The lenticular nucleus (nucleus lent ifonnis) the extraventricular part of the 

 corpus striatum -is embedded in the white substance of the cerebral hemisphere. 

 1 1 is somewhat pyriform in shape, not being so long as the caudate nucleus, and neither 

 having a tail nor extending so far forwards. Its lower ,-urface i- separated from the 

 inferior cornu of the lateral ventricle by the white substance of the roof of that cornu, 

 and by the tail of the caudate nucleus, and. further forwards, the anterior commissure 

 passes through its base. Its outer surface is rounded and conforms both in extent 

 and curvature with the surface of the insula, from which it is separated by the fibres 



ui. 638. CORONAL SECTION OF TELECENPHALON PASSING THROUGH FRONTAL LOBES AND 



ANTERIOR PORTION OF CORPUS STHIATI M. 

 (From mounted specimen in the Anatomical Department of Trinity College, Dublin.) 



Loxtir- 



TODIHAL 



FISSVHK 



OLFACTORY TRACT 



of the external capsule and the intervening claustrum. Its oblique upper and inner 

 surface is adapted to the outer .surface of the internal capsule, and it comes to a 

 rounded a pex in the angle formed by the internal capsule and a plane parallel with the 

 base of the hemisphere. In both horizontal and coronal (transverse) sections through 

 its middle it resembles a compound biconvex lens. Internally this appeal-am- 

 produced by two vertically curving lamina' of white substance, an external and an 

 internal medullary lamina, which divide its substance irTto three zones: the two 

 inner /ones t oget her form an area, t riangular in *ect ion, known as t he globus pallidus; 

 the outer, larger and darker, concavo-convex zone is the putamen. Radiating fibres 

 from the medullary lamina- extend into the /ones, especially those of the globus 

 pallidus. These zones disappear in transverse sections of the anterior portion of the 

 lent ictilar nucleus ((ig.ti.'iS), due to the fact that the larger putamen alone compi 

 thi> portion and alone becomes continuous with the caudate nucleus. 



Connections. --Both nuclei of the corpus stri.-itum become continuous with the . 

 in the region of the anterior perforated Mtbsl.-mre, and the putamcn of the lenticular nucleus may 

 blend with the anterior p.-irt of tlie II.-IM- <ii t lie el.-mstrum. 'I lie following :trc the principal 

 con nei-t ions: i I i I ibres arising in tlie nuclei which join the internal capsule to reach the cerebral 

 cortex, and fibres arising in the cortex which dcs( end I y the lame ci HIM 1" the cells of the 



