Blood supply to the colon and rectum

The blood supply to the colon originates from the SMA and the IMA. The SMA arises approximately 1 cm below the celiac artery and runs inferiorly toward the cecum, terminating as the ileocolic artery. The SMA gives rise to the inferior pancreaticoduodenal artery, several jejunal and ileal branches, the middle colic artery, and the right colic artery.
As a general rule, the middle colic artery arises from the proximal SMA and supplies blood to the proximal to midtransverse colon. However, it occasionally provides the predominant blood flow to the splenic flexure.
The right colic artery supplies blood to the mid-distal ascending colon. In anatomical studies, the right colic artery arises independently from the SMA in 28% of individuals, which is depicted in this figure. More frequently, the right colic artery arises with, or as a branch of, the middle colic, ileocolic, or left colic arteries. The right colic artery is absent in 13% of individuals.^[1]
The ileocolic artery supplies blood to the distal ileum, cecum, and proximal ascending colon.
The IMA arises approximately 6 to 7 cm below the SMA. The IMA gives rise to the left colic artery and sigmoid arteries continuing as the superior rectal (hemorrhoidal) artery. It is largely responsible for supplying blood distal to the transverse colon.