FUNCTIONS OF THE CEREBRAL HEMISPHERES 495 



the action of strychnine, or the toxin of tetanus. After administration 

 of either of these it is impossible to evoke inhibition of any muscle. 



FIG. 225. 



Anus & Vagina 



Toes 



Sulcus 

 , centra/is 



Knee 

 Hip . 



Abdomen 

 ^Chest 



Shoulder 

 Elbow " 

 Wrist " 



Finders 

 & thumb 



Ear-*''-' / , 

 Eyelid s Closure , 



Nose of j a w Qp en ing \ 



of jaw Vocal 



cords Mashcarion 



Sulcus centra/is 



FIG. 226. 

 Sulc. Central. Anu3 t "* *^* 



Salccattcso 



Sulc.oarieto 

 occip. 



Sulc.calcarin. 



C.S.S. dd. 



FIG. 225, outer surface ; FIG. 226, inner surface of brain of chimpanzee, 

 showing movements obtained by excitation of the motor areas. 

 (SHEBBINGTON.) 



Excitation of the cortical centre for the movements of the jaw causes 

 contraction of both closers and openers of the jaw, i.e. a strife in 

 which the stronger masseter muscles predominate, so that the jaw is 

 firmly closed. 



