266 



ANATOMY OF THE CBNTEAL NEBTOUS SYSTEM. 



most posterior portion of the inferior limb of the corpus callosum, the rostrum. 

 Between these two parts lies the inner wall of the hemisphere, the ventral portion 

 of which is designated as the area Brocse, the more dorsal part as the septum pel- 

 lucidum. The ventriculus septi is visible between the two walls o.f the septum. 

 The anterior horn of the ventricle is now widely opened, and the head of the nucleus 

 caudatus is cut through its greatest expanse. Lateral to this the fibers of the in- 

 ternal capsule pass down from the frontal pole, with which there is associated in 

 exactly this region the large fiber-syatem passing from the nucleus caudatus to the 

 thalamus, the radiatio atrio-thalamica. 



Pes of third frontal 

 gyrus 



Capaulaext. 



\ Fiss. Sylvii s- 

 L'jbus oif. post. 

 Claustrum 



Fig. 172. 



Externally to the internal capsule, here still interrupted by many bands of 

 gray matter, lies the most anterior part of the putamen. Then follows laterally 

 the eapsula externa, the claustrum, and the medulla and cortex of the insula. The 

 fasciculus uncinatus is lost in the first. This section already strikes the anterior 

 end of the Sylvian fissure. 



The entire dorsal half of the section is occupied by the medullary masses that 

 here arise from the three frontal convolutions. 



They consist, for the most part, of association-fibers that connect the regions 

 of the hemisphere with one another, more especially such fibers as belong to the 

 frontal lobe itself, but there ' are some longer fibers also, as the fasciculus arcuatus 



