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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.

Inferior mesenteric artery
Sigmoid colon and rectum, showing distribution of branches of inferior mesenteric artery and their anastomoses. (Inferior mesenteric artery labeled at center.)
Abdominal part of digestive tube and its attachment to the primitive or common mesentery. Human embryo of six weeks. (Inferior mesenteric artery labeled at bottom right.)
Precursorvitelline arteries
Sourceabdominal aorta
Branchesleft colic artery, sigmoid branches, superior rectal artery
Veininferior mesenteric vein
Latinarteria mesenterica inferior
Anatomical terminology


The IMA branches off the anterior surface of the abdominal aorta below the renal artery branch points, and approximately midway between these and the aortic bifurcation (into the common iliac arteries), L3 vertebral level.

The IMA has the following branches:

Branch notes
left colic artery supplies descending colon
sigmoid branches the most superior being described as 'the superior sigmoid artery'
superior rectal artery effectively the terminal branch of the IMA (the continuation of the IMA after all other branches)

All these arterial branches further divide into arcades which then supply the colon at regular intervals.

Associated veinsEdit

The IMA is accompanied along its course by a similarly named vein, the inferior mesenteric vein, which drains into the splenic vein.

The IMV therefore drains to the portal vein and does not fully mirror the course of the IMA.

Surgery and pathologyEdit

The IMA and/or its branches must be resected for a left hemicolectomy.

A horseshoe kidney, a common (1 in 500) anomaly of the kidneys, will be positioned below the IMA.

Additional imagesEdit

External linksEdit