582 



THE NERVOUS SYSTEM 



bound the fissure of Rolando and those on the inner side of the hemispheres 

 which correspond thereto, and possibly the frontal lobe in front of the pre- 

 central convolution. 



The position of the centers is probably much the same as in the monkey's 

 brain, those for the leg above, those for the arm, face, lips, and tongue from 

 above downward. Destruction of these parts causes paralysis, corresponding 

 to the district affected, and irritation causes contractions of the muscles of the 



P. CALL O SUM 



LOBE- 



FIG. 413. Diagram of Certain Connections of the Frontal, Temporal, and Occipital Lobes. 

 Founded on the observations of Flechsig, Ferrier, and Turner. (Cunningham.) 



same part. Again, a number of cases are on record in which aphasia, or the 

 loss of power of expressing ideas in words, has been associated with disease of 

 the posterior part of the lower or third frontal convolution on the left side. 

 This condition is usually associated with paralysis of the right side, right 

 hemiplegia. 



This district of the brain, particularly the convolutions bounding the 

 fissure of Rolando, is now generally known as the motor area; and there is no 

 doubt whatever that from this area pass the nerve fibers which proceed to the 

 spinal cord, and are there represented as the pyramidal tracts. 



