SOLAR OR EPIGASTRIC RLEXUS. 639 



pulmonary artery, and having' received an accession of fibres from the deep 

 cardiac plexus follows the course of the left or anterior coronary artery. 



The jjoitcrior cnronarij jjlexus, derived chiefly from the left part of the deep 

 cardiac plexus, but joined by nerves from the right portion of that plexus sur- 

 rounding the branches of the right coronary artery accompanies them to the 

 back of the heart. 



Nervous filaments ramify in great number under the lining membrane of the 

 heart. They are not so easily distinguished in man as in some animals. In the 

 heart of the calf or the lamb they are distinctly seen without dissection, i-unnino- 

 in lines which cross obliquely the muscular fibres. ■ Remak was the first to observe 

 that these branches are furnished with small ganglia, both on the surface and 

 in the muscular substance. (Miillers " Archiv," 1844.) For a description of the 

 Ganglia and Nerves of the Heart from original observations, see I. Bell Pettigrew, 

 *' Physiol, of the Circulation," kc, 1874, p. 293. 



SOIiAE, CR EPIGASTRIC PLEXUS. 



The solar or epigastric plexus, which is the largest of the prevertebral 

 centres, is placed at the upper part of the abdomen, behind the stomach, 

 and in front of the aorta and the pillars of the diaphragm. Surrounding 

 the origin of the coeliac axis and tlie upper mesenteric artery, it occu- 

 pies the interval between the suprarenal bodies, and extends downwards 

 as far as the pancreas. The plexus consists of nervous cords, with 

 several ganglia of various sizes connected with them. The large 

 splanchnic nerves on both sides, and some branches of the pneumo- 

 gastric, terminate in it. The branches given off from it are very 

 numerous, and accompany the arteries to the principal viscera of the 

 abdomen, constituting so many secondary plexuses on the vessels. 

 The diaphragmatic, coeliac, mesenteric, and other plexuses are recog- 

 nised, which follow the corresponding arteries. 



Semilunar ganglia. — The solar plexus contains, as already men- 

 tioned, several ganglia ; and by the presence of these bodies, and their 

 size, it is distinguished from the other prevertebral plexuses. The 

 two principal ganglionic masses, named semilunar, though they have 

 often little of the form tlie name implies, occupy the upper and outer 

 part of the plexus, one on each side, and are placed close to the supra- 

 renal bodies by the side of the coeliac and the superior mesenteric 

 arteries. At the upper end, which is expanded, each ganglion receives 

 the great splanchnic nerve. 



Diaphragmatic Plexus. — The nerves (inferior diaphragmatic) composing this 

 plexus are derived from the upper part of the semilunar ganglion, and ai-e larger 

 on the right than on the left side. Accompanying the arteries along the lower 

 surface of the diaphragm, the nerves sink into the substance of the muscle. 

 They furnish some filaments to the suprarenal body, and join with the spinal 

 phrenic nerves. 



At the right side, on the imder surface of the diaphragm, and near the supra- 

 renal body, there is a small ganghon. {gaiir/Iion diajjhragmaticum.) which marks 

 the jimction between the phrenic nerves of tbe spinal and sympathetic systems. 

 From this small ganglion filaments are distributed to the vena cava, the supra- 

 renal body, and the hepatic plexus. On the left side the ganglion is wanting, 

 but some filaments are prolonged to the hepatic plexus. 



Suprarenal Plesus. — The suprarenal nerves issue from the solar plexus and 

 the outer part of the semilunar ganghon, a few filaments being added from 

 the diaphragmatic nerve. They are short, but numerous in comparison with the 

 size of the body which they supply : they enter the upper and inner parts of 

 the suprarenal capsule. These nerves are continuous" below with the renal 

 plexus. The plexus is joined by branches from one of the splanchnic nerves, 

 and presents a ganglion {gangl. sjjlancloiico-svjyrarenale) , where it is connected 



