312 



THE NERVOUS SYSTEM 



the same spot in the cortex is always followed by the 

 same movement in the same animal. Those portions of 

 the cortex, therefore, whose stimulation results in motion, 

 are called motor areas. Speaking generally, these motor 

 areas may be said to occupy the portion of the cortex 

 about the fissure of Rolando and along the middle surface, 

 or edge, of the hemispheres. Particular movements of 

 head, trunk, and limbs are associated with particular spots 

 in the surface of this region, as shown inf^ig. 138. The 

 area controlling articulate speech, that is, the movements 



ii 



fig. 138. Diagrams illustrating localization of function in 

 the cerebrum. 



I outer surface of left hemisphere. 

 II inner surface of right hemisphere. 



Motor areas are shaded. 

 Cc corpus callosum. 

 Fr frontal lobe. 



Oc occipital lobe. 

 Pa parietal lobe. 

 Ro fissure of Rolando. 

 Sy Sylvian fissure. 

 Te temporal lobe. 



of tongue, lips, etc., in speech, lies adjacent to the Sylvian 

 fissure on the lowest frontal convolution. And, what is 

 peculiar to this cortical area for speech, it appears to be 

 confined to a single hemisphere in most cases the left 

 instead of being bilateral as are other parts of the 

 brain. 



455. Sensory Areas in the cortex are less definitely 

 located than are the motor areas. Broadly speaking, they 

 lie behind the motor surfaces. 



