38 SURGICAL APPLIED ANATOMY. [Chap. in. 



ascending frontal and ascending parietal convolutions; 

 the upper and anterior part of .the superior parietal 

 lobule, and a part of the mesial surface of the brain 

 (over the paracentral lobule and a part of the quadrate 

 lobe). The area for the foot lies in the anterior part 

 of the district. 



The upper limb. The middle third of the 

 ascending parietal and ascending frontal convolutions. 

 The shoulder centre lies in the upper part of the area, 

 the elbow lower down, and the hand in a still lower 

 part of the district. 



The face. The upper part of the lower third of 

 the ascending parietal and ascending frontal convolu- 

 tions. The centre for the angle of the mouth is in 

 the upper segment of this area. 



The tongue and lips. The lowest part of the 

 ascending frontal convolution. 



The area of motor speech. The tongue area and 

 adjacent part of the third frontal convolution. 



The area of the sense of hearing occupies the 

 posterior part of the first temporo-sphenoidal con- 

 volution. 



Of the brain generally little has to be said. In 

 a surgical sense, it presents itself simply as a large 

 mass of soft tissue that may be damaged by shaking 

 as gelatine may be shaken in a case. As it is of very 

 yielding structure, and does not entirely fill the 

 cranial cavity, it may, as it were, be th-rown about 

 within the skull, and be damaged by collision with its 

 walls. -Of the exact mechanism of concussion or 

 shaking of the brain little is known, and it cannot be 

 said that experiments, such as those of M. Gama, 

 with a bulb of isinglass within a glass matrass, tend to 

 throw much light upon the subject. In contusion or 

 bruising of the brain, it is noticed that the lesion is 

 very much more frequently situate on the under sur- 

 face, both as regards the cerebrum and cerebellum, 



