Veins of the Trunk. 



457 



496. Arteries and veins of a piece of small 



intestine. 



The vena portae 



(portal vein) (see Figs. 497 

 and 49S) collects the blood 

 from the whole digestive tube 

 from the cardia on as far as 

 the m. levator ani, from the 

 pancreas, the gall bla<lder 

 and the spleen. Its trunk 

 arises behind the caput pan- 

 creatis, on the left and poste- 

 rior surface of the pars supe- 

 rior duodeni, from the union 

 of the V. mesenterica supe- 

 rior and the v. lienalis; it 

 is 2 3 cm long and runs 

 upward in the lig. hepato- 

 duodenale, behind the a. he- 

 patica and the hepatic and 

 biliary ducts, to the porta 

 hepatis ; there it divides into 

 a right and left branch one 

 for each half of the liver. 

 Its roots follow, in general, 

 the branches of the arteries 

 of the same name and are 

 supplied with valves only in 

 their finer subdivisions im- 

 mediately after their exit 

 from the wall of the stomach 

 and intestine. 



1 . V. mesenterica 

 superior (see Figs. 497 and 

 498) runs on the right side 

 of the a. mesenterica supe- 

 rior arises from nvmierous 

 vv. iniestinales (from the 

 small intestine), from the 

 r. ileocolica, vv. colicac 

 dexirae , v. pancreatico- 

 duodenalis , vv. duodeiiales, 

 vv. pancreuticae , v. cotica 

 media and v. gastroepiploica 

 dextra. The intestinal veins 

 anastomose with one another 

 veiy much as the arteries do 

 but more frequently. 



2. T. mesenterica inferior (see Figs. 497 and 49S) collects its blood from the 

 v. haemorrhoidalis superior, the vv. sigmoideae and the v. colica sinistra. Its peripheral 

 course agrees with that of the a. mesenterica inferior; its trunk however separates from this 

 and goes in a curved direction upward and to the right behind the peritonaeiun (frequently in 

 the plica duodenojejunalis) and behind the pancreas; it usually opens into the v. lienalis, 

 fi-equently into the v. mesenterica superior, sometimes at the point of junction of the two. 



3. y. lienalis (see Figs. 497 and 498) is formed by the union of the veins of the 

 spleen with the v. gastroepiploica sinistra and with the vv. gastricue breves; it runs from 

 the left to the right beneath the a. lienalis and behind the pancreas, and in its course receives 

 several pancreatic veins. 



