

THE NERVOUS SYSTEM 



297 



FIG. 151 THE BRAIN OF A MONKEY 



Showing the parts of the brain that control 

 movements of different parts of the body. 

 (Horsley and Schafer) 



of the middle, superficial part of the cerebrum have been par- 

 ticularly investigated and it has been shown that some of these 

 control the muscles of the 

 arm, others those of the 

 leg, those of the neck, 

 those of the eye and so 

 on. The whole surface of 

 the cerebrum can not be 

 mapped out in this way. 

 Figure 151 shows the main 

 areas of the brain and the 

 parts of the body which 

 they control. All parts of 

 the brain cortex have not 

 yet been proved to have 

 clearly defined uses. In- 

 deed, there are on record 

 instances in which, through 

 accidents, parts of the 

 human brain have been 

 removed, and yet the in- 

 jured person showed no 

 unfavorable effects, in fact, 

 almost entirely- recovered. 



THE CEREBELLUM AND 

 ITS FUNCTIONS 



We have already noticed 

 that the external surface 

 of the cerebellum shows 

 a great complex of nar- 

 row ridges, separated by 

 grooves. If this organ is 

 cut open, the cut surface shows, as does the cerebrum, the 

 white and gray matter, but it is arranged somewhat 



FIG. 152. A SECTION OF THE CERE- 

 BELLUM 



Highly magnified. Some cells in this organ 

 have especially long and numerous den 

 drites. (Obesteiner) 



