THE CEREBRUM. 501 



4. The arm area may be subdivided as follows: (a) an area supe- 



riorly which controls the movements of the shoulder; (b) an area 

 posteriorly and below this, which controls the movements of the 

 elbow; (c) an area anteriorly and below the preceding, govern- 

 ing the movements of the wrist and fingers; (d) an area pos- 

 teriorly and below governing the movements of the thumb. 



5. The face area may be divided into an upper part, comprising 



about one-third, and a lower part, comprising the remaining 

 two-thirds. In the upper part are areas governing the move- 

 ments of the opposite angle of the mouth and of the lower face. 

 In the lower part anteriorly there is an area governing the move- 



FIG. 225. DIAGRAM OF THE MOTOR AND SENSOR AREAS ON THE MESIAL SUR- 

 FACE OF THE MONKEY BRAIN. (After H or shy and S chafer.) 



ments of the vocal membranes or bands (the laryngeal area); 

 posteriorly areas governing the opening and closing of the 

 mouth, the protrusion and retraction of the tongue. 

 The Sensor Areas of the Monkey Brain. From experiments 

 made on the brains of monkeys, Ferrier, Schafer, Horsley, and many 

 others have mapped out, though not with the same degree of definite- 

 ness and certainty, the sensor areas, stimulation of which gives rise to 

 sensation, destruction to loss of sensation. A diagrammatic repre- 

 sentation of these areas is shown in Fig. 224 and Fig. 225. 



The tactile area or area of tactile perception has not been accu- 

 rately or definitely located. Ferrier assigned it to the hippocampal 

 region. Schafer and Horsley assigned it to the limbic lobe, and 

 especially to that portion known as the gyrus fornicatus, as destruction 



