PORTAL VEIN. 335 



The pyloric vein (tig. 125, /) lies with the pyloric branch of the Pyloric 

 hepatic artery along the lower part of the small curvature of the vem- 

 stomach, and opens into the portal vein opposite the duodenum. 



The splenic vein (tig. 125) is of large size, and is formed by the Splenic 

 union of branches from the spleen. It rims below the artery, and vem: 

 under cover of the pancreas, to the front of the vena cava, where it 

 joins the superior mesenteric vein (6) to form the vena portse. 



Between its origin and termination it receives branches corre- tributaries, 

 sponding with the following arteries, vasa brevia (g), left gastro- 

 epiploic (e\ and pancreatic. The inferior mesenteric and coronary 

 veins (d] sometimes open into it. 



The PORTAL VEIN (vena portae, fig. 125, a, also fig. 123) is formed Portal vein : 

 by the union of the splenic and superior mesenteric veins. Its origin origin ; 

 is placed behind the head of the pancreas, and in front of the inferior 

 vena cava. The vessel is about three inches long, and ascends 

 beneath the first part of the duodenum, and then between the layers course and 

 of the small omen turn, to the transverse fissure of the liver, where it re 

 divides into a right and a left branch. While in the small omentum 

 it lies behind the hepatic artery and bile-duct. 



The right branch is shorter and larger than the left, and ramifies branches ; 

 in the right lobe of the liver. 



The left branch gives an offset to the Spigelian lobe, and enters 

 the left half of the liver. 



In its course the portal trunk is joined by the coronary and pyloric and tribu- 

 veins from the stomach ; and the cystic vein from the gall-bladder tanes - 

 enters the right branch. 



This vein commences by tributaries from the viscera of the abdomen, Peculiarities 

 like any other vein ; but it has no valves, and it ramifies through vein? 

 the structure of the liver in the same manner as an artery. Its 

 radicles communicate with the systemic veins on some parts of the 

 intestinal tube, but more particularly on the rectum. 



Dissection. The common bile-duct will now be traced upwards 

 and downwards, the duodenum being raised up from the right and 

 thence to the left as required. 



BILE-DUCTS. T 'wo hepatic ducts issue at the transverse fissure of Right and 

 the liver (tig. 131, p. 346), one from the right and the other from the SJctt** 11 " 

 left lobe, and unite to form the following : 



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

 at its termination the duct of the gall-bladder, the union of the two duct 

 giving origin to the common bile-duct. 



The common bile-duct (fig. 131, bd) is about three inches long. Common 

 It descends almost vertically beneath the upper portion of the blle ' duct : 

 duodenum ; then passing between the pancreas and the second course * nd 

 piece of the duodenum, it opens into this portion of the intestine termina- 

 at the inner side, and about the middle. While in the small tlon ; 

 omentum the duct lies to the right of the hepatic artery, and 

 somewhat before the portal vein. 



As it pierces the wall of the intestine it is joined commonly by the Ji ned by 

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



