Background. Branching pattern of inferior mesenteric artery (IMA) and pattern of vascular supply to the left colon and rectosigmoid areas, though important during colorectal surgery, display interethnic variations. Further, these regions have notable vascular “weak points” reported to be highly susceptible to ischemic colitis. This study aimed at evaluating the branching pattern of IMA in a black African population. Materials and Methods. Fifty-seven formalin-embalmed cadavers (28 Male, 27 Female) were studied. The length, branching pattern, and diameter of IMA at its origin were recorded. Results. IMA mean length and diameter at origin were ？mm and ？mm, respectively. IMA most frequently branched into left colic artery and a common sigmoid trunk in 23 cases while the classical branching pattern was observed in only 7 cases. Colic marginal artery was absent at the splenic flexure and sigmoid colon in 7 and 5 cases, respectively. Arc of Riolan was observed in 9 cases. Conclusion. Branching pattern of IMA shows variations from the previously reported cases which might help account for some of the untoward outcomes observed following colon surgery. An angiographic study to further delineate functionality of the arterial anastomoses in this region is recommended. 1. Introduction Arterial supply to the left colon and rectosigmoid colon is from the inferior mesenteric artery (IMA) classically by means of left colic artery (LCA), 2-3 sigmoid branches, and superior rectal artery. IMA originates from the front of the abdominal aorta, near its left margin just below the third part of the duodenum at the level of 3rd lumbar vertebra. It runs downwards arching slightly to the left, and as it crosses the left common iliac, its name arbitrarily changes to the superior rectal (or hemorrhoidal) artery. Pattern of branching however is reported to deviate from this classical description [1–5]. Detailed knowledge of the anatomical variations of the visceral branches of the abdominal aorta is of extreme clinical importance, particularly, when performing laparoscopic abdominal surgery. Further, colonic vascular supply has some weak areas which have been reported to be highly predisposed to ischemic colitis [6–8]. Griffiths’ point at the left colic flexure [9, 10] and the Sudeck’s point at the rectosigmoid region [4, 11, 12] are notable examples. In the presence of stenotic or occlusive disease of IMA or superior mesenteric artery (SMA), the presence of collateral channels between either artery is critical for maintaining the integrity of vascular supply to the affected
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