Chap. XIX] 



THE NERVOUS SYSTEM 



393 



Function of the cerebrum. — The nerve-centres which govern 

 all our mental activities and the coordination of movements are 

 centred in the cerebrum. These centres are the seat of reason, 

 intelligence, will, memory, and all the higher emotions and 

 feelings. 



Localization of brain function. — As the result of numerous 

 experiments on animals, and close observation of individuals 

 suffering from cerebral diseases or wounds, physiologists have been 

 able to localize certain areas in the brain which control motor and 

 sensory activity. They have also been able to gain some knowl- 



FiG. 188. — Localization of Function in the Cerebral Cortex. 

 ■ " Surgical Anatomy.") 



(Woolsey's 



edge of the areas in the cerebrum which are concerned with the 

 higher mental activities. 



Names of areas. — That portion of the cerebrum which governs 

 muscular movement is known as the motor area, the portions 

 controlling sensation as the sensory areas, and those connected 

 with the higher faculties, such as reason and will, as association 

 areas. 



Motor areas. — The surface of the brain assigned to the func- 

 tion of motion is the posterior part of the frontal lobe, i.e. the 

 gray matter immediately in front of the fissure of Rolando. 



A knowledge of the motor area enables physicians and surgeons, 

 in many cases of convulsions or paralysis, to locate the exact por- 

 tion of the brain that is affected, by close observation of the part 



