From the S2, S3 and S4 arise the pudendal nerve and parasympathetic fibers whose electrical potential supply the descending colon and rectum, urinary bladder and genital organs.
12.
The "'left colic flexure "'or splenic flexure ( as it is close to the spleen ) is the sharp bend between the transverse colon and the descending colon.
13.
This means that even when an enema cleans the colon rather easily, stool keeps on passing fairly quickly from the cecum to the descending colon and the anus.
14.
It begins at the level of the iliac crest, where it is continuous with the descending colon, and ends in the sigmoid colon at the superior aperture of the lesser pelvis.
15.
Their branches supply the lower part of the descending colon, the iliac colon, and the sigmoid or pelvic colon; anastomosing above with the left colic, and below with the superior hemorrhoidal artery.
16.
The muscles of the colon then move the watery waste material forward and slowly absorb all the excess water, causing the stools to gradually solidify as they move along into the descending colon.
17.
Of note, the splenic flexure, or the junction between the transverse and descending colon, is supplied by the most distal portions of both the inferior mesenteric artery and superior mesenteric artery, and is thus referred to medically as a shock.
18.
The final branch which is important for the digestive system is the inferior mesenteric artery, which supplies the regions of the digestive tract derived from the hindgut, which includes the distal 1 / 3 of the transverse colon, descending colon, sigmoid colon, rectum, and the anus above the pectinate line.
19.
The mesentery associated with the ascending colon and descending colon is resorbed, bringing these parts of the colon into close contact with the body wall . " To reconcile these differences, several theories of embryologic mesenteric development including the " regression " and " sliding " theories have been proposed, but none has been widely accepted.
