AREA OF FACE, MOUTH, THROAT, AND LARYNX. 741 



A considerable amount of differentiation is obtained within the area, 

 as was observed already by Eerrier in his first experiments. Thus he 

 got, on stimulation of the upper part of the area over the ascending 

 frontal gyrus, retraction and elevation of the opposite angle of the 

 mouth, due to the action of the zygomatic muscles, and from a part 



FIG. 338. Diagrams of the lateral and mesial surfaces of the monkey's brain, showing 

 the effects obtained from stimulation of the excitable areas. 



just below this, elevation of the opposite ala of the nose and upper lip 

 associated with depression of the lower lip. These movements when 

 performed bilaterally produce a snarl, fully exposing the canine teeth ; 

 an expression very characteristic and frequent in monkeys when 

 alarmed. Excitation of the part of the ascending parietal gyrus on a 

 level with the two regions just described, produced " retraction of the 

 angle of the mouth. The action is that of the platysma myoides, and 



