TRIBUTARIES OF THE PORTAL VEEN. 543 



supplied by that vessel, viz., from the small intestine, and from the ascending and 

 transverse parts of the colon. The trunk, formed by the union of its several 

 branches, inclines upwards and to the right side, passing in front of the third part 

 of the duodenum and behind the pancreas, where it joins with the splenic vein to 

 form the vena portae. The superior mesenteric vein is also joined, close to its ter- 

 mination, by the right gastro-epiploic vein from the great curvature of the stomach. 



The branches of the inferior mesenteric vein correspond with the ramifica- 

 tions of the artery of the same name. They commence at the lower part of the 

 rectum in the hremorrhoidal plexus, and unite into a single vessel near the sigmoid 

 flexure of the colon. From this point the vein proceeds upwards beneath the peri- 

 toneum, lying to the left of the aorta, and then passing behind the pancreas, it 

 inclines to the right to terminate in the angle formed by the junction of the splenic 

 and superior mesenteric veins, or in the adjacent part of either of these vessels. 



The splenic vein, a vessel of large size, commences by five or six branches 

 which issue separately from the hilum of the spleen, and soon unite to form a single 

 trunk. It is directed from left to right beneath the pancreas, in company with the 

 splenic artery, below which it is placed. After crossing in front of the aorta it joins 

 the superior mesenteric vein, nearly at a right angle. It receives gastric branches 

 (vasa brevia) from the left portion of the stomach, the left gastro-epiploic vein, some 

 pancreatic branches, and frequently the inferior mesenteric and coronary veins. 



The pyloric vein is a small vessel which accompanies the pyloric branch of the 

 hepatic artery on the small curvature of the stomach, and opens into the portal vein 

 at a variable level. 



The coronary vein of the stomach is of considerable size, and runs with the 

 artery of the same name along the small curvature of the stomach to the cardiac 

 orifice, where it receives branches from the oesophagus, and then, turning to the 

 right, passes across the front of the spine to open into either the lower end of the 

 portal vein or the adjoining part of the splenic vein. 



There are no valves in the portal vein or in its larger tributaries, although such are known 

 to exist in some animals. Valves are however present in the child in the veins of the 

 stomach and of the wall of the intestine ; but according to Hochstetter and Bryant they early 

 become insufficient, and in the adult to a great extent disappear. (F. Hochstetter, " Ueber 

 das normale Vorkommen von Klappen in den Magenverzweigungen der Pfortader," Arch. f. 

 Anat., 1887 ; W. S. Bryant, u Valves in the Veins of the Human Intestines," Boston Med. and 

 Surg. Journ., 1888 ; H. Koeppe, " Muskeln und Klappen in den Wurzeln der Pfortader," Arch, 

 f. Physiol., 1890.) 



Varieties. The coronary cein is sometimes very small, or absent, when the pyloric rein 

 is proportionately enlarged. The pyloric vein may either descend to the superior mesenteric 

 vein, or ascend independently to the liver : it is often represented by two or three smaller 

 branches. The coronary vein has been seen passing up through the small omentum to join 

 the left division of the portal vein. (On the different modes of termination of the coronary 

 and inferior mesenteric veins, and their relative frequency, see W. J. Walsham, ' ; Observations 

 on the Coronary Veins of the Stomach," Journ. of Anat., xiv, 1880 ; C. M. Fiirst, " Vense 

 coronaria3 ventriculi," Hygiea, 1881 : F. Treves, " The Anatomy of the Intestinal Canal and 

 Peritoneum in Man," 1885 ; F. Hochstetter, Arch. f. Anat., 1886 ; Report of Committee of 

 Collective Investigation of Anat. Soc., Journ. Anat. xxv, 1890.) 



Accessory portal veins. This name has been given by Sappey to a number of small vessels 

 which collect blood from the areolar tissue and peritoneal folds around the liver, and partly 

 open into branches of the portal vein, partly penetrate directly into the substance of the liver ; 

 through anastomoses formed by the radicles of these vessels the portal vein is put into direct 

 communication with the phrenic and azygos veins. There are also constantly one or more 

 small veins which descend from the left division of the portal vein along the round ligament 

 of the liver towards the umbilicus. According to Baumgarten the chief of these is a vestige 

 of the umbilical vein, the lumen of which is as a rule not completely obliterated, but for a 

 considerable part of its extent persists in the adult as a fine canal occupying the centre of the 

 round ligament, and receiving minute branches from the abdominal wall. Other small veins 

 on the surface of the ligament are called parumbilical, and open either into the remains of 

 the umbilical vein or directly into branches of the portal vein. These vessels form connections 



