Figure 29a.

Within the mesentery, the main arterial stem of superior mesenteric artery (SMA) describes an arc that spans the distance between the horizontal duodenum and the ileocecal junction, where the SMA terminates by anastomosing with one of its own branches, the ileocolic artery. Of the arteries to the large intestine, the middle colic artery (MCA) is the first to arise from the right side of the SMA. This branch is usually given off at the inferior margin of the neck of the pancreas before the SMA enters the mesentery. The MCA passes into the transverse mesocolon. In this image, the jejunal branches are seen going away from the probe, and the inferior pancreaticoduodenal artery is seen as the first branch arising from the right side of the SMA coming toward the probe. The second branch coming from the right side of SMA is MCA, which is seen to enter the transverse mesocolon. MCA: Middle colic artery, INFR PDA: Inferior pancreaticoduodenal artery, IMV: Inferior mesenteric vein