When the inferior cervical ganglion has given branches to the heart, the dorsal sympathetic chain is continued on from it in a backward direction, between the costo-vertebral articulation and the pleura.

As it passes backwards there appears upon it a number of very small ganglia, one of which is situated against each of the vertebral openings through which pass the spinal nerves.

Each ganglion receives one or two small afferent filaments from the inferior branches of those nerves.

In its course backwards it gives off the great splanchnic nerve at a point corresponding to the seventh intercostal space. From this point it proceeds backwards, and in its course receives a small branch from each of the ganglia.

It then proceeds to the side of the aorta between the cseliac axis and the large mesenteric artery, where it has upon it the semilunar or solar ganglion. This is a body of considerable size and importance. It is joined to its fellow on the opposite side by a large wide branch and numerous smaller ones, resulting in the formation of a plexus beneath the aorta termed the solar plexus.

After receiving some branches from the pneumogastric nerve, this plexus splits up into several smaller plexuses, which form a net-work round the arteries, and through them the sympathetic is distributed to the several abdominal organs. In this way we get the gastric plexus to the stomach, the hepatic plexus to the liver, duodenum, pylorus, and pancreas, a splenic plexus to the spleen, and also a plexus to the stomach. A large plexus, the anterior mesenteric, surrounds the artery of that name, and is distributed over the organs supplied by it. A renal plexus encircles the renal artery and accompanies it to the kidney.

The lumbo-aortic plexus passes backward along the under surface of the aorta, and mixes its fibres with the posterior mesenteric plexus.

The great splanchnic nerve leaves the dorsal chain about the seventh intercostal space. From this point it receives a few afferent fibres from the ganglia, commencing with the sixth, and continues to do so irregularly up to the sixteenth. Behind, the great splanchnic ends in the solar plexus.

The lesser splanchnic nerve is made up of two or three small branches proceeding from the last dorsal ganglion; these collect into a short thin branch, which joins the solar plexus or the renal and suprarenal plexuses.