THE SYMPATHETIC NERVOUS SYSTEM 349 



cardiac plexus lies in close relation to the arch of the aorta, and from it sub- 

 ordinate plexuses are continued along the coronary arteries. It receives the 

 three cardiac sympathetic nerves from the cervical portion of each sympathetic 

 trunk, as well as branches from both vagus nerves (Figs. 248, 257). The pregan- 

 glionic fibers of the vagus terminate in synaptic relation with the cells of the 

 cardiac ganglia. They convey inhibitory impulses which are relayed through 

 these ganglia to the cardiac musculature (Fig. 250). The cardiac sympathetic 

 nerves contain postganglionic fibers which take origin in the cervical sympa- 

 thetic ganglia; and they relay accelerator impulses, coming from the spinal cord 

 by way of the upper white rami and sympathetic trunk to the heart (Fig. 250). 

 The pulmonary and esophageal plexuses of the vagus are also to be regarded as 

 parts of the sympathetic system (Fig. 257). 



The celiac plexus (solar plexus) is located in the abdomen in close relation 

 to the celiac artery (Figs. 248, 257). It is continuous with the plexus which 

 surrounds the aorta. Subordinate portions of the celiac plexus accompany 

 the branches of the celiac artery and the branches from the upper part of the 

 abdominal aorta. These are designated as the phrenic, suprarenal, renal, 

 spermatic or ovarian, abdominal aortic, superior gastric, inferior gastric, he- 

 patic, splenic, superior mesenteric, and inferior mesenteric plexuses. The celiac 

 plexus contains a number of ganglia which in man are grouped into two large 

 flat masses, placed one on either side of the celiac artery and known as the 

 celiac ganglia. These ganglia are bound together by strands which cross the 

 median plane above and below this artery. Somewhat detached portions of 

 the celiac ganglion, which lie near the origin of the renal and superior mesenteric 

 arteries, are known respectively as the aorticorenal and superior mesenteric 

 ganglia. In addition, there is a small mass of nerve-cells in the inferior mesen- 

 teric plexus close to the beginning of the inferior mesenteric artery. This is 

 known as the inferior mesenteric ganglion. 



Preganglionic fibers reach the celiac plexus from two sources, namely, from 

 the white rami by way of the sympathetic trunk and splanchnic nerves and from 

 the vagus nerve (Fig. 257). Most if not all of the preganglionic fibers contained 

 in the splanchnic nerves terminate in the ganglia of the celiac plexus. At the 

 lower end of the esophageal plexus the fibers from the right vagus nerve become 

 assembled into a trunk which passes to the posterior surface of the stomach and 

 the celiac plexus. The fibers of the left vagus pass to the anterior surface of 

 the stomach and to the hepatic plexus (Fig. 257). It is probable that the pre- 

 ganglionic fibers of the vagus do not terminate in the ganglia of the celiac plexus, 



