Anomalous origins of colic arteries.

The topography of the celiac trunk and superior and inferior mesenteric arteries was studied by dissection in 27 embalmed cadavers. Variant vascular patterns were noted in four subjects. These consisted of: (1) an accessory right hepatic artery from the superior mesenteric artery, (2) an anomalous middle colic artery from the proximal segment of the splenic artery, and (3) two instances of an accessory left colic artery originating from the superior mesenteric artery. The precarious course of the middle colic artery (coming from the splenic artery) and its dominance in the formation of the marginal artery were thought to predispose the ascending and transverse colon to an increased risk of vascular damage. These cases also illustrate two variant patterns of formation of the marginal artery. In the case of the anomalous middle colic artery, the only contribution of the superior mesenteric artery to the marginal artery was through the anastomosis of its ileocolic branch with the right branch of the aberrant middle colic artery. In subjects with accessory left colic arteries, the superior mesenteric artery played a dominant role in the formation of the marginal artery by contributing the accessory left colic artery, which supplied the splenic flexure and the proximal part of the descending colon. These arterial variations underscore the importance of doing vascular studies prior to major abdominal surgery.