CAPSULA INTERNA, COEPUS STEIATUM, INTEHBRAIN-GANGLIA. 355 



A very instructive section may be made which gives an idea of the origin of the 

 fibers found in the pes. Take a fresh brain and cut into the crus cerebri perpen- 

 dicularly until the substantia nigra is met with. Then turn the knife and cut 

 horizontally through both hemispheres in a direction obliquely upward and forward. 

 The section upon which is based the illustration shown in Fig. 258 is made in a similar 

 manner. For the passing of the fibers from the internal capsule into the pes, see 

 Fig. 175. 



Psalteni ni j 

 Puh nai 

 PinPil 

 Corp. qua J II 



AqiKc la t |-"- 

 Corp. geni'' n 1 

 Corp. goii 1 t 



Laqueub snp 



Subst nign 



Pes pei-lan nl 



Faso. oooip.-front. 

 \ucl. caudat. 



I Latticed layer of 

 I thalamus 

 Nucl. lentif. 

 I Rad. occip.-thal. 

 I (optic tract; 



Kad. temporo-thal. 

 Nucl. caudatus 

 I jmm. ant. 

 L iruu Ammoais 



Fig. 165. — Frontal section through the forebrain and interbrain close to the place 

 where the fibers of the capsula interna become fibers of the pes pedunculi. 



The tracts from the cortex form the chief mass of the pes. Dorsally 

 there is added to them a small tract which, coming from the corpus striatiim, 

 terminates in a ganglion situated dorsal to the pes, in the substantia nigra. 

 It is the stratum intermedium 'pedunculi. 



We will now turn our attention to the corpus striatum and the fiber- 

 systems arising from it. 



This large ganglion, situated at the base of the forebrain, is divided 

 by the fibers of the internal capsule arising in the cortex into the nucleus 



