Which of the following statements regarding the vasculature of the colon and rectum is/are correct?

a. The middle colic artery is a branch of the superior mesenteric artery

b. The inferior mesenteric artery supplies the descending and sigmoid segments of the colon

c. An complete anastomotic arcade paralleling the colon wall is present in only 15 to 205 of individuals

Two major arterial systems supply the colon. The right colon is predominantly supplied by the superior mesenteric artery. The major branches of this artery that perfuse the right colon include the ileocolic branch, which supplies the ileocecal junction; the right colic, which supplies the ascending colon; and the middle colic artery, which supplies the hepatic flexure and the transverse colon to its midpoint. The left colon is predominantly supplied by the inferior mesenteric artery, which derives its origin from the abdominal aorta. The distal transverse colon and the descending colon obtain their blood supply from the left colic branch of the inferior mesenteric artery, while the sigmoid colon obtains its blood supply from sigmoidal branches. The colic arteries bifurcate and form vascular arcades so that the resultant marginal Drummond artery forms an anastomosis between the superior mesenteric artery and the inferior mesenteric artery. However, considerable anatomic variation exists with respect to this arterial arcade, and a complete anastomosis is present in only 15% to 20% of people.