Chap. III.] 



CRANIAL CONTENTS. 



39 



than on any other part (Prescott Hewett). To this 

 statement, however, there is the striking exception 

 that those parts of the base of the cerebrum that rest 

 upon the large basal collection of the cerebro- spinal 

 fluid are the least often contused. These parts include 

 the medulla, the pons, and the interpedunculav space. 



PO.F 



Fig. 8. The Motor Centres of the Cortex. (Modifie I from Gowers.) 



J|| Area of the leg. ..-:.- Area of motor speech. 



Er= Area of the upper limb. 



/// Area of the face. ++ Sensory region, area of hearing 



\\\ Area of the tongue. Otncr markings as in Fig. 7. 



The brain is very lavishly supplied with blood- 

 vessels. The main arterial trunks (vertebral and 

 internal carotid) are both rendered tortuous before 

 entering the skull, with the object probably of 

 diminishing the effects of the heart's systole upon the 

 brain. On entering, they are almost immediately 

 blended into an anastomosing circle (circle of Willis), 

 which has the effect of equalising the cerebral circu- 

 lation. Ligature of one common carotid may produce 

 no effect upon the brain, although the mortality after 

 this operation is mainly due to cerebral complications- 



