184 



PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



separated one from the other as taught by Gall, but intimately 

 associated and to a certain extent dependent one on another for 

 their full functional importance. 



The Motor Area. The first experiments of Fritsch and Hitzig 

 disclosed the location of a cortical region in the dog which upon 

 stimulation gave definite movements. The later experiments of 

 Ferrier, Schafer, Horsley, and Beevor, particularly upon the apes, 

 gave reason for believing that this motor area surrounds the fissure, 

 of Rolando and extends inward upon the mesial surface of the cere- 

 brum. Its exact boundaries marked out by careful stimulation of 



yf J<*w Opening Vo cal Mastication, 

 oj~fQ,u> cords 



Fig. 81. Location of motor areas in brain of chimpanzee. (Sherrington and Green- 

 baum.) The extent of the motor areas is indicated by stippling; it lies entirely in front 

 of the fissure of Rolando (sulcus centralis). Much of the motor area is hidden in the sulci. 

 The regions marked eyes indicate the areas whose stimulation gives conjugate movements 

 of the eyeballs. It is doubtful, however, whether these represent motor areas proper. 



the region in monkeys was more or less verified upon man, since in 

 operations upon the brain it was often necessary to stimulate the 

 cortex in order to localize a given motor area. By these means 

 charts have been made showing the cortical area for the musculature 

 of each part of the body. It was found that in general the distri- 

 bution of the areas lies along the fissure of Rolando and follows the 

 order of the cranial and spinal nerves. Within each area smaller 

 centers may be located by careful stimulation; thus, the hand and 

 arm area may be subdivided into centers for the wrist, fingers, 

 thumb, etc. More recently Sherrington and Greenbaum,* making 



* " Reports of the Thompson- Yates and Johnston Laboratories," 4, 351, 

 1902; 5, 55, 1903. 



