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TEXT-BOOK OF PHYSIOLOGY. 



face and tongue. Collectively these areas are known as the motor 

 area or motor zone; and as it is ranged along the Rolandic fissure, it 

 is sometimes termed the Rolandic area. 



The experiments of Horsley and Schafer added additional facts 

 and enabled them to construct a new diagrammatic representation of 

 the motor area and more accurately define the special areas upon 

 the lateral and mesial aspects of the brain of the monkey. The 

 boundaries of the general and special areas, as determined by these 

 observers, will be readily apparent from an examination of Fig. 224. 

 Their experiments have enabled them also to subdivide the general 

 into special areas as follows : 



FIG. 224. DIAGRAM OF THE MOTOR AND SENSOR AREAS ON THE LATERAL SUR- 

 FACE OF THE MONKEY BRAIN. (After Horsley and S chafer.') 



1. The head area or area for visual direction into areas excitation of 



which causes " opening of the eyes, dilatation of the pupils and 

 turning the head to the opposite side with conjugate deviation 

 of the eyes to that side." 



2. The leg area may be subdivided into (a) an area both on the 



lateral and mesial surfaces which presides over the movements of 

 the hip and thigh ; (b) an area in the posterior part which presides 

 over the movements of the legs and toes; (c) an area in the 

 paracentral lobule for the movements of the hallux or great toe. 



3. The trunk area, situated largely on the mesial surface, may be 



subdivided into an anterior and a posterior area, which respec- 

 tively preside over the movements of the spinal column as arch- 

 ing and rotation, and the movements of the pelvis and tail. 



