40 SURGICAL APPLIED ANATOMY. [Chap. in. 



One carotid and the two vertebrals would appear to be 

 able to bring enough blood to the brain, which blood 

 will be as evenly distributed as hitherto by the circle 

 of Willis. Both common carotids have been ligatured, 

 or one carotid has been secured, when its fellow of the 

 opposite side has been occluded by disease, and no 

 marked cerebral disturbances have followed. In HO 

 case, however, has the patient recovered when the 

 interval between the closing of the two vessels was 

 less than a few weeks. The vertebral arteries can 

 carry a sufficient amount of blood to the brain if only 

 the strain be thrown upon them gradually, and the 

 brain be allowed to accommodate itself slowly to the 

 change. Plugging of any of the smaller cerebral 

 arteries by emboli, as a rule, leads at once to a marked 

 disastrous result. Such embolism is met with in 

 surgery in connection with aneurism of the common 

 carotid. In simply examining such aneurisms, a 

 little piece of the clot contained in the sac has been 

 detached, has been carried up into the brain, and has 

 produced a plugging of one of the cerebral vessels. 

 Thus, hemiplegia has followed upon the mere exami- 

 nation of a carotid aneurism, as in a case recorded 

 by Mr. Teale, of Leeds. Fergusson's treatment of 

 aneurism at the root of the neck, by displacing the 

 clots by manipulation, has been abandoned on this 

 same score. In the second case treated by manipula- 

 tion by this surgeon, a case of subclavian aneurism, 

 paralysis of the left side of the body followed at once 

 upon the first handling of the tumour. 



The pulsations of the brain may be communicated 

 to any tumours or collections of fluid that reach the 

 surface of the brain through an aperture in the skull. 

 Such pulsations are synchronous with the arterial 

 pulse, but the sphygmographic tracings of the cerebral 

 pulsation exhibit also the "respiratory curve." 



Although wounds of the brain bleed freely, the 



