Sunday, May 29, 2011

Superior Mesenteric Artery

The superior mesenteric artery originates at the anterior surface of the abdominal aorta, supplying oxygenated blood to the intestine from the lower part of the duodenum through two-thirds of the transverse colon, and the pancreas to the left colic flexure. The superior mesenteric artery runs along behind the neck of the pancreas, then gives off five branches: 1) inferior pancreaticoduodenal artery; 2) middle colic artery, which supplies to the transverse colon; 3) right colic artery, which travels to ascending colon; 4) ileocolic artery, which supplies the last part of ileum, cecum, and appendix; 5) intestinal arteries, which runs to ileum and then branches to jejunum.

The superior mesenteric artery usually forms an angle of approximately 45° (range, 38-56°) with the abdominal aorta, and the third part of the duodenum crosses caudal to the origin of the superior mesenteric artery, coursing between the superior mesenteric artery and aorta. Any factor that sharply narrows the aortomesenteric angle to approximately 6-25° can cause entrapment and compression of the third part of the duodenum as it passes between the superior mesenteric artery and aorta, resulting in superior mesenteric artery syndrome.