Corpus: Inferior mesenteric vein

The inferior mesenteric vein is a tributary branch of the splenic vein. It drains the descending parts of the colon (descending colon, sigmoid colon, rectum) via the sinus colic vein, sigmoid veins and rectal venous plexus.

The inferior mesenteric vein runs retroperitoneally in the paraduodenal plica - separate from the inferior mesenteric artery of the same name. Ascending from the rectum, it accompanies the descending colon and crosses under the transverse colon and the duodenojejunal flexure. Below the pancreatic collum, it flows into the splenic vein, via which it supplies the venous blood of the left "intestinal abdomen" to the portal vein.

In portal hypertension, a compensatory portocaval bypass circulation is formed via the inferior mesenteric vein. The blood that backs up into the vein flows via the inferior rectal veins of the rectal venous plexus into the internal pudendal veins and further via the internal iliac veins into the inferior vena cava. Venous hypertension of the rectal veins can lead to the formation of haemorrhoids.