Inferior mesenteric artery is one of the major arteries of the alimentary canal. It supplies a significant portion of the digestive system including part of transverse colon, left colic flexure, descending colon, sigmoid colon, rectum and the upper half of the anal canal.
Origin and course of inferior mesenteric artery:
The inferior mesenteric artery arises from the abdominal aorta about 1.5 inches above its bifurcation into the right and left common iliac arteries. After its origin, the inferior mesenteric artery runs downward and to the left and crosses the left common iliac artery. Here it becomes the superior rectal artery, which is simply its continuation into the pelvis.
Branches of the inferior mesenteric artery:
Left colic artery:
It runs upward and to the left to supply the distal part of the transverse colon. It also supplies the left colic flexure and the upper part of descending colon, by dividing into ascending and descending branches.
These are two to three in number, which supply the lower part of descending colon and the sigmoid colon.
Superior rectal artery:
It is a continuation of the inferior mesenteric artery as the latter crosses the left common iliac artery. It descends into the pelvis behind the rectum, where it supplies the rectum and the upper half of anal canal. It ends by anastomosing with the middle rectal and inferior rectal arteries.