Inferior mesenteric artery

Artery: 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.)
Latin	arteria mesenterica inferior
Gray's	subject #154 609
Source	abdominal aorta
Branches	left colic artery, sigmoid branches, superior rectal artery
Vein	inferior mesenteric vein
Precursor	vitelline arteries
MeSH	Mesenteric+Artery,+Inferior

In human anatomy, the inferior mesenteric artery, often abbreviated as IMA, supplies 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). The territory of distribution of the IMA is more or less equivalent to the embryonic hindgut.

Branching

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 veins

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 pathology

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

A horseshoe kidney, a common (1 in 600) anomaly of the kidneys, will be positioned below the IMA.

Additional images

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  The abdominal aorta and its branches.

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  The inferior mesenteric artery and its branches.

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  Abdominal portion of the sympathetic trunk, with the celiac plexus and hypogastric plexus.

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  Duodenojejunal fossa.

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  Posterior abdominal wall, after removal of the peritoneum, showing kidneys, suprarenal capsules, and great vessels.

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  Front of abdomen, showing surface markings for arteries and inguinal canal.

External links

• SUNY Figs 39:02-05 - "Branches of the inferior mesenteric artery."
• SUNY Labs 40:11-0103 - "Posterior Abdominal Wall: Branches of the Abdominal Aorta"
• SUNY Anatomy Image 7924
• SUNY Anatomy Image 7997
• SUNY Anatomy Image 8407
• SUNY Anatomy Image 8659
• Atlas of anatomy at UMich abdo_wall70 - "Posterior Abdominal Wall, Dissection, Anterior View"
• sup&infmesentericart at The Anatomy Lesson by Wesley Norman (Georgetown University)