676 



THE CEREBRUM 



right motor points controlling the muscles of the eyes, produces a 

 deviation of both eyes toward the left. In this case, therefore, an 

 activation of the right internal and left external recti results which 

 is associated with an inhibition of the right external and left internal 

 recti. The same holds true of other movements which are carried 

 on with the help of corresponding muscles on the two sides of the 

 body, such as the erection and flexion of the trunk, the approximation 

 of the jaws, and the contraction of the muscles of the abdominal wall. 

 Clearly, these movements must be bilaterally controlled and coordi- 

 nated. A bilateral representation is also had in the case of the respi- 

 ratory muscles, because, as will be pointed out later, the destruction 

 of one motor area does not affect the respiratory movements. 



The observations of Sherrington and Greenbaum^ have shown that 

 in the anthropoid apes the motor area is confined to the anterior 



SulacaUoso 



SulcparieCo 

 occip. 



Sulc. Central. ^""^ * ^'^^ 



\ ./ StUc.jjrecenCrmarff. 



SulccalcaTin. 



C.S.S. del. 



Fig. 342. — Mesial Surface of Chimpanzee, Showing that the Motor Areas also 

 Dip into the Longitudinal Fissure. {Sherrington and Greenbaum.) 



central convolution, but this discovery is not wholly new, because 

 a very similar condition has already been proved by Fritsch and Hitzig 

 to exist in the monkey. These 'tests have been extended to man by 

 Bartholowand Sciamanna, but particularly by Terrier (1890), Horsley, 

 Brevior (1890), and Bechterew (1899). The more recent work of F. 

 Krause^ in particular te/ids to prove that the localization in man is 

 very similar to that found in the anthropoid apes. The motor points 

 are concentrated in the precentral convolution and neighboring por- 

 tions of the frontal furrows and permit of the production of very 

 specialized movements. 



The Motor Area is a True Center. — Fritsch and Hitzig character- 

 ized the motor area as a center for the production of muscular motion. 



1 Proc. Royal See, London, Ixxii, 1903. 



2 Lewandowsky, Die Funktionen des zentralen Nervensystems, Jena, 1907. 



