Il6 THE CEREBRUM. 



transversely, and, from above downward, one inch and a half. 

 It is placed anterior and external to the thalamus and forms 

 the third of the great divisions of the cerebral hemisphere, viz., 

 the neopallium, the rhinencephalon and the corpus striatum. It 

 is a reddish-gray body, and its streaked appearance is due to the 

 white capsular fibers which pierce it. The striated body is an 

 important relay hi the motor conduction path and one of less 

 importance in the sensory path. The internal capsule divides 

 it into two nuclei, namely, the lentiform nucleus (extraventricular 

 part), and the caudate nucleus, which is seen in the boundary of 

 the lateral ventricle. Anterior to the free borders of the supe- 

 rior and inferior capsular laminae, the two nuclei are united with 

 each other, with the anterior perforated substance and with the 

 lower end of the claustrum. 



The lentiform nucleus (nucleus lentijormis] occupies the 

 cone-like cavity of the internal capsule, by whose laminae it is 

 separated from the ventricle (Fig. 32). It is shorter fore and 

 aft than the caudate nucleus. It resembles a biconvex lens with 

 a somewhat thickened anterior border, when viewed in horizontal 

 section (Fig. 31). In transverse vertical section through its 

 center, it is triangular in shape. The hypotenuse and base are 

 formed, respectively, by the superior and inferior laminae of the 

 internal capsule. The external capsule forms the perpendicular 

 and separates the lentiform nucleus from the claustrum. The 

 latter is a thin sheet of isolated gray matter, found just medial to 

 the island (of Reil). In extent and position, fore and aft, the 

 island and lentiform nucleus coincide. The lentiform nucleus 

 is subdivided by two white laminae, parallel with its external sur- 

 face, into three zones. (Fig. 30). The outer zone, called the 

 putamen, is deeply pigmented, and, like the caudate nucleus, is of 

 a reddish-gray color; but the two inner zones, having less pig- 

 ment, are of a pale yellowish tint. They form the globus pallidus. 



The nucleus caudatus (the tailed nucleus) is a pear-shaped 

 body of reddish-gray color, situated on the perimeter of the inter- 

 nal capsule (Figs. 30, 32 and 40). It is the intraventricular 

 part of the striated body and forms a strip of the ventricular floor 

 along the outer wall. The head (capuf) of the caudate nucleus 



