A 51-year-old complains of abdominal pain of 2-month duration. A CT scan of the patient's abdomen is shown. An angiogram indicates that several arteries of the gastrointestinal tract are occluded due to atherosclerosis, producing bowel ischemia. Which of the following arteries is most likely occluded in the CT scan?

(c) Source: GAS 336; GA 147, 160 The arrows in the CT scan point to the descending colon. Therefore, the left colic artery, which supplies the descending colon, is the one most likely occluded in the CT scan. The middle colic, right colic, and ileocolic artery supply the ascending colon, and the marginal artery provides an anastomosis between branches of the superior mesenteric artery and inferior mesenteric artery.