The superior mesenteric artery (SMA) is one of the anterior unpaired branches of the abdominal aorta. It is close to one centimeter in diameter at its origin and is about 15 centimeters in length. At its origin, just inferior to the celiac trunk, it is directed anteroinferiorly, hugged by the head and uncinate process of the pancreas. The SMA passes over the transverse (3rd segment) of the duodenum where it is accompanied by the inferior mesenteric vein.
The SMA provides supply to the duodenum, jejunum, ileum, the right side of the colon (cecum, vermiform appendix, and ascending colon), and the transverse colon. The jejunal and ileal arteries traverse within the layers of the mesentery.
As the SMA passes over the third portion of the duodenum, and because of the angle formed between the SMA and the abdominal aorta, it slightly compresses the duodenum. In very rare cases, this angle can be so acute as to cause doudenal obstruction requiring surgery. This rare syndrome is called “SMA compression syndrome” was first described in 1861 by Baron Carl Freiherr Von Rokitansky (1804 -1878). To see an article with a better image of the SMA-abdominal aorta angle click here.
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Image modified from the original by Gray (1918)
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