598 SYMPATHETIC NERYE. 



Mr. Beck) from all the thoracic ganglia above the sixth. These roots unite to 

 form a large round cord of considerable size. It descends obliquely inwards in 

 front of the bodies of the vertebrae along the posterior mediastinum, perforates the 

 crus of the Diaphragm, and terminates in the semilunar ganglion, distributing 

 filaments to the renal plexus and supra-renal gland. 



The Lesser Splanchnic nerve is formed by filaments from the tenth and 

 eleventh ganglia, and from the cord between them. It pierces the Diaphragm 

 with the preceding nerve, and joins the coeliac plexus. It communicates in the 

 chest with the great splanchnic nerve, and occasionally sends filaments to the 

 renal plexus. 



The Smallest or Renal Splanchnic nerve arises from the last ganglion, and, piercing 

 the Diaphragm, terminates in the renal plexus and lower part of the coeliac plexus. 

 It occasionally communicates with the preceding nerve. 



A striking analogy appears to exist between the splanchnic and the cardiac 

 nerves. The cardiac nerves are three in number; they arise from the three 

 cervical ganglia, and are distributed to a large and important organ in the thoracic 

 cavity. The splanchnic nerves, also three in number, are connected probably 

 with all the dorsal ganglia, and are distributed to important organs in the abdominal 

 cavity. 



The Epigastric or Solar plexus supplies all the viscera in the abdominal cavity. 

 It consists of a dense network of nerves and ganglia, situated behind the stomach 

 and in front of the aorta and crura of the Diaphragm. It surrounds the coeliac 

 axis and root of the superior mesenteric artery, extending downwards as low as 

 the pancreas, and outwards to the supra-renal capsules. This plexus, and the 

 ganglia connected with it, receive the great splanchnic nerve of both sides, part 

 of the lesser splanchnic nerves, and the termination of the right pneumogastric. 

 It distributes filaments, which accompany, under the name of plexuses, all the 

 branches from the front of the abdominal aorta. 



The semilunar ganglia of the solar plexus, two in number, one on each side, 

 are the largest ganglia in the body. They are large irregular gangliform masses, 

 formed by the aggregation of smaller ganglia, having interspaces between them. 

 They are situated by the side of the cceliac axis and superior meseuteric artery, 

 close to the supra-renal glands, the one on the right side lying beneath the vena 

 cava; the upper part of each ganglion is joined by the greater and lesser 

 splanchnic nerves, and to the inner side of each the branches of the solar plexus 

 are connected. 



From the solar plexus are derived the following : 



Phrenic or diaphragmatic plexus. Supra-renal plexus. 



Coeliac plexus. Kenal plexus. 



Gastric plexus. Superior mesenteric plexus. 



Hepatic plexus. Spermatic plexus. 



Splenic plexus. Inferior mesenteric plexus. 



The phrenic plexus accompanies the phrenic artery to the Diaphragm, which 

 it supplies, some filaments passing to the supra-renal gland. It arises from the 

 upper part of the semilunar ganglion, and is larger on the right than on the left 

 side. In connection with this plexus, on the right side, at its point of junction 

 with the phrenic nerve, is a small ganglion (ganglion diaphragmaticum). This 

 ganglion is placed on the under surface of the Diaphragm, near the supra-renal 

 gland. Its branches are distributed to the vena cava, supra-renal gland, and the 

 hepatic plexus. The ganglion is absent on the left side. 



The supra-renal plexus is formed by branches from the solar plexus, from the 

 semilunar ganglion, and from the splanchnic and phrenic nerves, a ganglion being 

 formed at the point of junction of the latter nerve. It supplies the supra-renal 

 gland. The branches of this plexus are remarkable for their large size, in com- 

 parison with the size of the organ they supply. 



The renal plexus is formed by filaments from the solar plexus, the outer part 



