Superior mesenteric artery
In human anatomy, the superior mesenteric artery arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk, and supplies the intestine from the lower part of the duodenum through two-thirds of the transverse colon, as well as the pancreas.
Structure
It arises anterior to lower border of vertebra L1 in an adult. It is usually 1 cm lower than the celiac trunk. 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:- left renal vein - travels between the left kidney and the inferior vena cava.
- the third part of the duodenum, a segment of the small intestines.
- uncinate process of pancreas - this is a small part of the pancreas that hooks around the SMA.
SMA Branches
| Branch | Supplies |
| inferior pancreaticoduodenal artery | head of the pancreas and to the ascending and inferior parts of the duodenum |
| intestinal arteries | branches to ileum, branches to jejunum |
| ileocolic artery | supplies last part of ileum, cecum, and appendix |
| right colic artery | to ascending colon |
| middle colic artery | to the transverse colon |
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 relevance
- 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.
- 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.
- The SMA can compress the left renal vein, leading to nutcracker syndrome; and/or the third part of the duodenum, leading to superior mesenteric artery syndrome.
Additional images