Frontal view of the superior mesenteric artery and its branches. The large vessel (blue) beside the SMA is the superior mesenteric vein. A considerable number of different branching patterns exist.
In the adult, the SMA arises anterior to inferior border of vertebra L1 (transpyloric plane). It is usually 1 cm lower than the celiac trunk.
Course and relations
It initially travels in an anterior/inferior direction, passing behind/under the neck of the pancreas and the splenic vein. Located under this portion of the superior mesenteric artery, between it and the aorta, are the following:
The SMA typically runs to the left of its associated vein, the superior mesenteric vein. After passing the neck of the pancreas it starts giving off its branches.
The number of arterial arcades in the ileum is more than the number of arcades in the jejunum. [1]
The middle, right, and ileocecal branches anastomose with each other to form a marginal artery along the inner border of the colon. This artery is completed by branches of the left colic which is a branch of the inferior mesenteric artery.
Clinical significance
Compared to other vessels of similar size, the SMA is largely spared from the effects of atherosclerosis. This may be due to protective haemodynamic conditions.[citation needed]
Acute occlusion of the SMA almost invariably leads to intestinal ischemia and often has devastating consequences, with up to 80% of SMA occlusions leading to death.[2]