Origin

The inferior mesenteric artery originates from the very front of the abdominal aorta behind the third (horizontal) part of the duodenum at the level of L3 vertebra, about 3-4 cm above the end point (bifurcation) of the abdominal aorta.

Course And Branches

After appearing from the aorta, it runs downward and to the left behind the peritoneum to cross the end point of the left common iliac artery (medial to ureter) at which stage it becomes the superior rectal artery. The superior mesenteric artery provides rise to these branches:

  • Left colic artery.
  • Sigmoidal arteries (2 to 3 in number).
  • Superior rectal artery (continuation).

Distribution

The inferior mesenteric artery is the artery of hindgut, thus it provides all the parts of gut originated from hindgut, viz, left 1-third of the transverse colon, descending colon, rectum, and upper part of the anal canal.

The lowest sigmoidal artery anastomoses with the colic branch (first branch) of the superior rectal artery and this anastomosis is inadequate (weak point) in the marginal artery of the colon. Consequently, the point of origin of the last sigmoidal artery from the inferior mesenteric artery is termed critical point of Sudeck. For that reason, while ligating the inferior mesenteric artery it ought to be done proximal to Sudeck’s point to prevent ischemia and necrosis of the sigmoid colon and rectum.