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A MANUAL OP ANATOMY 



adjacent portions of the pancreas and duodenum. The vessel is 

 accompanied by an offshoot from the superior mesenteric sym- 

 pathetic plexus, and, when it arises from the first ramus intestini 

 tenuis, it passes behind the superior mesenteric artery. 



Superior Mesenteric Vein. — This vein is formed by tributaries 

 which return the blood from the parts of the intestinal canal supplied 

 by the superior mesenteric artery, and it receives in addition the 

 right gastro-epiploic vein. It ascends on the right side of the 

 superior mesenteric artery. After leaving the mesentery it passes 

 over the third part of the duodenum and uncinate process of the 

 pancreas, and finally behind the neck of the latter organ, where it 

 joins the splenic vein to form the vena portae. The vessel and its 

 tributaries are destitute of valves, so that the blood can regurgitate 

 in cases of portal obstruction. 



Superior Mesenteric Sympathetic Plexus. — ^This plexus is derived 

 from the solar plexus. It closely surrounds the superior mesenteric 



artery in the form 

 of a tough sheath, 

 and it furnishes 

 offshoots which 

 accompany all 

 the branches of 

 that vessel. 



Lymphatic 

 Vessels of Small 

 Intestine. — ^These 

 which are called 

 lacteals, originate 

 in the villi of the 

 mucous mem- 

 brane of the small 

 Fig. 313. — Portion of Jejunum with its Mesentery, i^^^estine (see p. 

 showingLacteal Vessels AND Mesenteric Glands. 79^)- They leave 



the wall of the 

 bowel at the mesenteric border, those of the jejunum exceeding in 

 number those of the ileum . Within the mesentery they take a course 

 inwards and upwards, becoming, in succession, the afferent and 

 efferent vessels of the groups of mesenteric glands. At the root 

 of the superior mesenteric artery the lacteals, which have now 

 emerged from the innermost mesenteric glands, terminate in from one 

 to four lymphatic trunks, which open into the receptaculum chyli. 

 Superior Mesenteric Glands. — ^These are about 150 in number, and 

 are situated within the mesentery proper and along the course of the 

 trunk of the superior mesenteric artery. In health their average size 

 is about that of a small pea, except along the course of the main 

 artery, where they are somewhat larger, and they are more numerous 

 in the jejunal than in the ileal mesentery. They receive the lacteals 

 from the lower part of the duodenum, the jejunum, and the ileum, 

 and also the lymphatics from the ascending and transverse colon. 

 There are no glands in the portion of mesentery close to the intestine 



