In
Human Anatomy , the , 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 (artery of Drummond). The territory of distribution of the IMA is more or less equivalent to the embryonic
Hindgut .
The IMA has the following branches:
- left colic artery
- sigmoid branches (the most superior being described as 'the superior sigmoid artery')
- superior rectal, 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.
The IMA branches off the anterior surface of the
Abdominal Aorta , approximately midway between the
Renal Artery branch points and the abdominal aortic
Bifurcation (into the
Common Iliac Arteries ). It 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.
The IMA and/or its branches must be resected for a left hemicolectomy.
A
Horseshoe Kidney , a rare (1 in 600) anomaly of the kidneys, will be positioned below the IMA.
