The coeliac or solar plexus is found behind the stomach, in front to the upper part of the abdominal aorta, and between the crura of the diaphragm. Closely associated with the plexus are the two semilunar (coeliac) ganglia. Each is placed upon a crus of the diaphragm and partially covered by the corresponding suprarenal gland. In addition, the inferior vena cava forms an important anterior relation of the right ganglion. Suspended from the lower pole of each is the aortico-renal ganglion. The plexus itself contains an indefinite number of minute ganglia. Certain nerves pass from the thorax to blend with the coeliac plexus. The right vagus furnishes several large branches to the plexus; the great splanchnic terminates in the superior extremity of the semilunar ganglion, while the lesser splanchnic joins the lower part of the aortico-renal ganglion. From the coeliac plexus filaments stream out over the aorta and its main branches to form subsidiary plexuses; other twigs are distributed to the abdominal surface of the diaphragm.

The aortic plexus is prolonged into the pelvis as the two hypogastric nerves.

Branches

(a)

Coeliac plexus,

Coronary plexus, to oesophagus and stomach. Splenic plexus, to spleen, stomach, and pancreas.

Hepatic plexus, to liver, biliary passages, stomach, duodenum, and pancreas.

(b) Phrenic plexus, to diaphragm, suprarenal plexus, and on the left side to oesophagus. It communicates with the phrenic nerves. A small ganglion, the phrenic, is found on the right side.

(c) Suprarenal plexus, to suprarenal gland.

(d) Renal plexus, the least splanchnic nerve terminates in this plexus. It furnishes twigs to the suprarenal plexus and supplies the kidneys.

(e) Superior mesenteric plexus, to small intestine and large intestine as far as the end of the transverse colon. (f) Spermatic or ovarian plexus, to testis in male, and Fallopian tube, ovary, and broad ligament in female. (g) Inferior mesenteric plexus, supplies descending colon, iliac colon, pelvic colon, and upper part of rectum.