In
human anatomy, the
inferior mesenteric artery, often abbreviated as
IMA, is the third main branch of the
abdominal aorta and arises at the level of
L3, supplying the
large intestine from the
left colic (or splenic) flexure to the upper part of the
rectum, which includes the
descending colon, the
sigmoid colon, and part of the rectum. Proximally, its territory of distribution overlaps (forms a
watershed) with the
middle colic artery, and therefore the
superior mesenteric artery. The SMA and IMA anastomose via the
marginal artery of the colon (artery of Drummond) and via
Riolan's arcade (also called the "meandering artery", an arterial connection between the left colic artery and the medial colic artery). The territory of distribution of the IMA is more or less equivalent to the embryonic
hindgut.