THORACIC GANGLIA. 669 



The great splanchnic nerve is of a white color, firm in texture, and bears a 

 marked contrast to the ganglionic nerves. It is formed by branches from the 

 thoracic ganglia between the sixth and tenth, receiving filaments (according to 

 Dr. 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 vertebra along the posterior mediastinum, perforates 

 the cms of the Diaphragm, and terminates in the semilunar ganglion, distri- 

 buting filaments to the renal plexus and suprarenal capsule. 



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 cceliac 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 

 cceliac 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 cceliac axis and root of the superior mesenteric artery, extending down- 

 wards as low as the pancreas, and outwards to the suprarenal 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 

 mesenteric artery, close to the suprarenal capsules: the one on the right side 

 lies 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. Suprarenal plexus. 



Cceliac plexus. Eenal 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 suprarenal capsule. It arises from 

 the upper part of the semilunar ganglion, and is larger on the right side 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 diaphragma- 

 ticum). This ganglion is placed on the under surface of the Diaphragm, near 

 the suprarenal capsule. Its branches are distributed to the vena -cava, supra- 

 renal capsule, and the hepatic plexus. There is no ganglion on the left side. 



The suprarenal 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- 



