SYMPATHETIC NERVE. 631 



centre of the sympathetic system. It consists of a series of 

 ganglia, more numerous on the right than the left side, 

 about an inch in length and presenting a semicircular form; 

 several of these are sometimes fused into one. They all 

 communicate and send off an immense number of radiating 

 filaments, constituting the solar plexus. 



This plexus (Fig. 203) is situated behind the stomach, 

 above the pancreas, and within the epigastric region, and 

 receives branches from the lesser splanchnic, the phrenic, 

 and the right vagus. From this central and great plexus, 

 nervous filaments proceed in every direction, and mostly 

 follow the course of the arteries, around each of which they 

 form a plexus, receiving its name from the artery it accom- 

 panies. Thus we have enumerated the following different 

 plexuses : 



The phrenic, composed of branches coming from the 

 solar plexus, accompanies the phrenic arteries to the dia- 

 phragm. 



The gastric plexus goes along the coronary artery to the 

 stomach, where it communicates with the vagi. 



The hepatic plexus takes the course of the hepatic artery 

 to the liver. Branches also accompany the vena portaa 

 and right gastro-epiploic artery to the greater curvature 

 of the stomach. 



The splenic plexus follows the splenic artery to the 

 spleen, sending off branches to the pancreas and head of 

 the stomach, and along the left gastro-epiploic artery to 

 the greater curvature of the stomach. 



The superior mesenteric plexus surrounds the superior 

 mesenteric artery, and its branches supply the small in- 

 testines, co3cum, ascending, and transverse colon. 



The renal plexus attends the renal arteries to the kid- 

 neys. This plexus gives off filaments to the supra-renal 

 capsules, called supra-renal plexus , and also filaments along 

 the spermatic artery, called the spermatic plexus, to the 

 testes of the male, and ovary of the female. 



The inferior mesenteric plexus follows the course of the 

 inferior mesenteric artery, and supplies the descending 



