Inferior mesenteric vein

Origin and course

The inferior mesenteric vein arises in the lower abdomen as a continuation of the superior rectal vein that drains the rectal (hemorrhoidal) venous plexus. The inferior mesenteric vein runs retroperitoneally, ascending from its origin to the left side. Along its course, it crosses the left psoas major muscle, the left ureter and left gonadal (testicular/ovarian) vessels. Upon reaching the left side of the duodenojejunal flexure, the inferior mesenteric vein curves to the right and passes posterior to the body of the pancreas. Here, it terminates by draining into the splenic vein, which then merges with the superior mesenteric vein to form the hepatic portal vein. Occasionally, the inferior mesenteric vein may drain into the superior mesenteric vein instead, or into its confluence with the splenic vein.

Tributaries and drainage area

Along its relatively long course across the abdominal cavity, the inferior mesenteric vein receives the sigmoid and left colic veins as tributaries. Thereby, the inferior splenic vein drains blood from the rectum, sigmoid, descending and distal transverse colon. Together, the superior and inferior mesenteric veins drain the majority of the gastrointestinal tract, from the stomach to the rectum.

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