Description: The sigmoid colon is the extension of the mobile descending colon that curves antero-inferiorly from the left side of the abdomen into the pelvis centrally, and connects with the rectum which terminates distally at the anal canal. The rectum courses above and below the most dependent part of the rectouterine pouch. Below, the rectum 'penetrates' the pelvic floor in the posterior pelvic triangle between the levator ani m. and the coccygeous m., encircled by the puborectalis m. to reach the anal canal. The circulation is via the inferior mesenteric a. (sigmoid colon), the superior and middle rectal a. (rectum). A plexus of recta veins drains the blood from the area via the superior rectal veins into the portal system, and the middle and inferior v. to the vena cava. Innervation is from L1-L3 via the hypogastric plexus. Parasympathetic n. from sacral plexus (S2-S4 ), and sympathetic n. from L1-L3 (arising in the lumbar chain ganglia), reach the s. colon and rectum along with the inferior mesenteric a.