450 DISSECTION OF THE ABDOMEN. 



This vein commences by roots in the viscera nbove mentioned, like any 

 other vein, but it is deficient in valves ; and it ramifies through the struc- 

 ture of the liver in the same manner as an artery. Its radicles communi- 

 cate with the systemic veins on some parts of the intestinal tube, but more 

 particularly on the rectum. 



BILE DUCTS. Two hepatic ducts issue at the transverse fissure of the 

 liver (fig. 158), one from each lobe, and unite to form the following : 



The common hepatic duct is an inch and a half long, and receives at 

 its termination the duct of the gall bladder, the union of the two giving 

 origin to the common bile duct. 



The common bile duct (ductus communis choledochus) is about three 

 inches long. It descends almost vertically beneath the upper transverse 

 portion of the duodenum ; then passing between the pancreas and the 

 vertical piece of the duodenum, it opens into this portion of the intestine 

 at the inner side, and above the middle. Whilst in the small omentum 

 the duct lies to the right of the hepatic artery, and somewhat before the 

 portal vein. 



Before piercing the coats of the intestine it is joined commonly by the 

 pancreatic duct, but the two may enter the duodenum separately. 



SYMPATHETIC AND VAGUS NERVES. 



SYMPATHETIC NERVE. In the abdomen, as in the thorax, the sympa- 

 thetic nerve consists of a gangliated cord on each side of the vertebral 

 column, and of prevertebral centres or plexuses, which furnish branches 

 to the viscera. 



Two prevertebral plexuses exist in the abdomen. One of these, the 

 epigastric, is placed behind the stomach, and supplies nerves to all the 

 viscera above the cavity of the pelvis. The other, the hypogastric plexus, 

 is situate in the pelvis, and distributes nerves to the pelvic viscera. 



The knotted or gan<?liated cord will be met with in a subsequent stage 

 of the dissection ; and only the great solar plexus with its offsets is tojbe 

 now examined. 



Dissection. To denude the epigastric plexus, the following dissection 

 is to be made : After the air has been let out of the stomach and duode- 

 num, the portal vein, the common bile duct, and the gastro-epiploic ves- 

 sels are to be cut through near the pylorus; and the stomach, duodenum, 

 and pancreas are to be drawn over to the left side. On raising the liver 

 the vena cava appears : the vein is to be cut across above the junction of 

 the renal vein with it, and the lower end is to be drawn down with hooks. 



Beneath the vein the dissector will find the large reddish semi-lunar 

 ganglion ; and mixed up with the nerves of the plexus are numerous 

 lymphatic glands, and a dense tissue, which require to be removed with 

 care. From its inner part he can trace the numerous nerves and ganglia 

 around the coeliac and superior mesenteric arteries, and the secondary 

 plexuses on the branches of those arteries. From the outer part of the 

 ganglion offsets are to be followed to the kidney, the suprarenal body, and 

 the diaphragmatic arteries : at its upper part the junction with the large 

 splanchnic nerve may be seen ; and deeper than the last, one or two smaller 

 splanchnic nerves may be observed in a fissure of the diaphragm, which 

 throw themselves into the coaliac and renal plexuses. 



The student should then trace the ending of the pneumogastric nerves 

 on the stomach. The left nerve will be found at the upper border in front 



