46 SURGICAL SHOCK 



rigidity of the abdominal wall frequently reminds us. 

 Chloroform, of course, does reduce the blood-pressure 

 after a time. 



Without venturing to formulate a cut-and-dried 

 theory, then, one may suggest that the nociceptive 

 impulses which bring about surgical shock do so by 

 inhibiting or paralyzing the important nuclei in the 

 region of the fourth ventricle and perhaps in the 

 cerebellum, which, as Sherrington and others have 

 shown, are continually sending impulses down the 

 spinal cord, maintaining its functional activity and 

 increasing muscular tone. When such inhibition 

 or paralysis takes place the functions of the cord 

 are greatly reduced, tone is abolished, and there- 

 fore, as a secondary result, the blood-pressure may 

 fall. The respiratory centre, and perhaps even the 

 vasomotor centre, share in this inhibition or 

 paralysis ; this is a very different conception from 

 that which takes exhaustion of the vasomotor 

 centre to be the prime cause of all the symptoms. 

 Death is due to accumulation of blood in the great 

 veins, so that the vis a tergo is no longer able to 

 provide a proper filling for the heart, especially as 

 the feeble respiratory movements fail to exert their 

 important pumping action. 



A very striking example of this sequence is met 

 with in what is called " the knock-out blow " in 

 pugilism, or rather, one of such blows. A vigorous 

 drive on the point of the lower jaw in a line from 

 the chin to the condyles is transmitted directly to 

 the labyrinth of the internal ear, and by way of the 

 vestibular nerve impulses reach the nuclei of which 



