THE BRAIN. 



505 



Between these lies the interual capsule, through which 

 pass fibers that spread out toward the cortex, as the corona 

 radiata. 



Pathology, especially, has shown that a lesion of the intra- 

 ventricular portion of the corpus striatum, and, ahove all, of 

 the internal capsule, is followed by failure of voluntary move- 

 ment (akinesia). It would appear tliat a great part of the 

 fibers from the motor area around the fissure of Eolando, pass 

 through the intra- ventricular parts of the corpus strig,tum, and 

 especially its internal capsule. But it is also to be borne in 

 mind that a large part of the fibers passing fromi the cortex 

 make connection with the cells of the corpus striatum before 

 reaching the cord. These facts render the occurrence of loss of 

 voluntary motor power coniprehensible. 



The fibers of the peduncles of the brain may be divided into 

 an interior or lower division (crusta), going mostly to the 



Fig. 36!!. — Transverse section of human brain (after Daiton). Tliis and the preceding 

 figure are somewhat diagrammatic. 1, pons Varolii; 2,2, crura cerebri; 3,3, in- 

 ternal capsule; 4, 4, corona radiata; 5, optic thalamus; 6, lenticular nucleas; 7, 

 corpus calloBUm. 



corpus striatum, and a posterior division (tegmentum), passing 

 principally to the optic thalami ; many, possihly most of tl|em, 

 ultimately reach the cortex. Many clinical observers do not 

 hesitate to speak of the optic thalamus as sensory in function. 



