The rectum begins where the taeniae coli of the sigmoid colon disappear and ends at the anus. The proximal rectum is located within the abdominal cavity. The pelvic rectum is located anterior to the sacrum. The anterior surface of the rectum is variably lined by peritoneum depending on the depth of the cul de sac. Anteriorly, the rectum is separated from the urogenital structures by the fascia of Denonvilliers. Posteriorly, the mesorectal fascia abuts the presacral fascia with a connection between the two, the rectosacral fascia. The arterial supply is from the superior, middle, and inferior rectal arteries. The rectum has dual venous drainage to the portal vein and to the vena cava. Anorectal lymphatic drainage is to three major collections of lymph nodes: superior rectal, iliac, and inguinal. The rectum is surrounded by a mesorectum encased by fascia.