Re-evaluation of the colic irrigation from the inferior mesenteric artery

156 abdominal preparations were explored by arteriography, corrosion and dissection. The arteria mesenterica inferior (AMI) ends by bifurcating into the two arteriae rectales superiores. The key to the interpretation of the AMI is the recognition of an arteria colosigmoidea that gives off one or more rami sigmoidei. In the presence of an arteria or ramus colic. sin. access, usually from the superior mesenteric artery, the left colic artery is absent, atrophic or displaced. The sigmoid branches (usually three) arise from the colosigmoid, the left colic or the distal portion of the AMI. Usually, the last sigmoid artery gives branch to the rectosigmoid colon. The rectosigmoid artery arises from the AMI between arteria sigmoidea ima and the terminal bifurcation of the former. It may be replaced by the descending branch of the a. sigmoidea ima. They irrigate an extensive part of the anterior wall of the bowel.