66 NERVOUS SYSTEM. 



The ganglions that occur in the wall of the viscera at the 

 terminal branches of roots from the great sympathetic serve 

 as a centre for partial movements of the visceral muscles, 

 and regulate, by way of illustration, the peristaltic contrac- 

 tions of the intestinal walls. Other ganglions (of Wrisberg, 

 semi-lunar, of the hypogastric plexus, etc.) might be con- 

 sidered as provisionary centres where the nervous action 

 coming from a higher point can be accumulated. The ma- 

 jority of the phenomena of the visceral functions have as 

 their nervous centre the spinal cord, and even in the vaso- 

 motor functions (see circulation) the sympathetic has only a 

 power of impression derived from the superior portion of the 

 spinal axis. The same may be said in reference to its influ- 

 ence on the heart, and most of the visceral reflex actions 

 whose centre is found in the spinal cord ; so that the expres- 

 sion "great sympathetic system" has at this present time 

 but little physiological signification. 



