The inferior mesenteric artery (Latin: arteria mesenterica inferior) is a visceral branch of the abdominal aorta that supplies the distal one-third of the transverse colon, the descending colon, the sigmoid colon, and most of the rectum.
The inferior mesenteric artery is the smallest of the three unpaired visceral branches arising anteriorly from the abdominal aorta. It originates at the level of the body of the vertebra L3.
In the beginning, the inferior mesenteric artery descends anteriorly along the aorta and then passes to the left as it continues inferiorly. It gives several branches on its way, including the left colic artery, several sigmoid arteries, and the superior rectal artery.
All these arterial branches further divide and create arcades that supply the colon at regular intervals.
On its course, the inferior mesenteric artery is accompanied by the inferior mesenteric vein, which flows into the splenic vein. The inferior mesenteric vein, therefore, drains into the portal system and does not fully mirror the course of the artery.