250 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



tracing its branches, tear the mesenteries which bind together the coils of the 

 intestine as far as necessary and also strip off fat and lymph glands. The 

 intestinal vein is the large vessel collecting from the greater part of the small 

 intestine. It runs in the middle of the mesentery, receiving many tributaries 

 in its course. The branches from the jejunum immediately beyond the 

 duodenum, however, enter the posterior pancreatico-duodenal vein. The very 

 large ileocaecocolic vein collects from the ileum, appendix, caecum, and ascend- 

 ing and transverse colons. Chief among its tributaries are: the appendicular 

 vein from the appendix; the anterior ileocaecal vein from the sacculus rotundus, 

 proximal part of the caecum, adjacent ileum, and ascending colon; and the 

 posterior ileocaecal vein from the distal part of the caecum, adjacent ileum, and 

 ascending colon. 



Draw, showing the portal system. 



Cat: The first tributary of the portal, on following the portal away from 

 the liver, is the coronary vein from the stomach. This lies in the curve between 

 pylorus and stomach and at the lesser curvature is formed by the union of many 

 branches from both sides of the stomach. At about the same level as the entrance 

 of the coronary vein, the anterior pancreatico-duodenal vein enters the portal; it 

 collects from the pancreas and duodenum. At the same level as the two preced- 

 ing, the right gastro-epiploic vein enters, coming from the pyloric region and greater 

 curvature of the stomach and adjacent greater omentum. The three veins just 

 described may enter the portal separately or may unite with each other in any 

 combination before entering the portal. Beyond the entrance of these small veins 

 the hepatic portal receives a large tributary, the gastro splenic vein. This passes 

 to the left in the substance of the pancreas receiving one or more small middle 

 gastro-epiploic veins from the stomach wall and omentum and a pancreatic vein 

 from the pancreas. Beyond these tributaries the gastrosplenic is formed by the 

 union of two main branches, the right and left splenic veins. The left splenic 

 vein passes in the gastrosplenic ligament along the spleen, receiving branches from 

 the spleen, the greater omentum, and several left gastro-epiploic veins from the 

 omentum and stomach. The right splenic vein comes from the right end of 

 the spleen, receiving also tributaries from the omentum and stomach wall. 

 Beyond the entrance of the gastrosplenic vein the portal is known as the superior 

 mesenteric vein. This soon receives a small posterior pancreatico-duodenal vein 

 from the pancreas and distal part of the duodenum ; next, the inferior mesenteric 

 vein from the descending colon and rectum; and then is seen to be formed by 

 numerous converging intestinal branches from the small intestine, caecum, and 

 ascending colon. The lymph glands lying along the superior mesenteric vein 

 as well as fat, should be removed in tracing the branches. 



Draw the hepatic portal system. 



It will be seen that the relations of the hepatic portal system are the same in mammals 

 as in all other vertebrates. The system conveys all of the venous blood from the digestive 



