190 HUMAN PHYSIOLOGY. 



4. The trunk area, situated largely on the mesial surface, contains anteriorly 

 centers governing the rotation and arching of the spine, while posteriorly 

 are found centers governing movements of the tail and pelvis. 



5. The head area, or area for -visual direction, contains centers excitation of 

 which causes "opening of the eyes, dilatation of the pupils, and turning 

 of the head to the opposite side, with conjugate deviation of the eyes to 

 that side." 



From experiments made on animals corrected by observations of lesions 

 of the human brain corresponding centers have been located in man as 

 shown in Fig. 29 and 30. 



CONCRETE CONCEPT 



FIG. 29. THE AREAS AND CENTERS OP THE LATERAL ASPECT OF THE HUMAN 

 HEMI-CEREBRUM. (C. K. Mills.) 



Center for Speech. Pathologic investigations have demonstrated that 

 the left third frontal convolution is of essential importance for speech. 

 Adjoining this convolution are the centers controlling the motility of the lips, 

 tongue, etc. In the majority of cases the speech centers are on the left side 

 of the brain, though in exceptional cases they are on the right side, especially 

 in left-handed persons. In deaf mutes this convolution is very imperfectly 

 developed, while in monkeys it is quite rudimentary. 



