The inferior mesenteric plexus is derived chiefly from the aortic plexus. It surrounds the inferior mesenteric artery, and divides into a number of secondary plexuses, which are distributed to all the parts supplied by the artery, viz. , the left colic and sigmoid plexuses, which supply the descending and sigmoid parts of the colon; and the superior hemorrhoidal plexus, which supplies the rectum and joins in the pelvis with branches from the pelvic plexuses. [ http://en.wikipedia.org/wiki/Inferior_mesenteric_plexus ]