RectumThe rectum is continuous with the sigmoid colon proximally at the level of the rectosigmoid junction (S3) and with the anal canal distally1. The rectum has a sacral curvature which follows the curve of the sacrum and coccyx1. Anorectal flexion is an S-shaped flexion that has a pronounced posteroinferior curvature anteroinferior to the tip of the coccyx and enters the pelvic diaphragm1. It is held by the puborectalis sling through the puborectalis muscle1. Finally, the rectum also presents lateral flexions due to the transverse rectal folds1. There is upper, middle and lower lateral flexion1.Relationships of the rectum1:• Lower o Pelvic diaphragm (levator ani) o Anococcygeal ligament• Anterolateral o Peritoneum of upper rectum• Anterior o Peritoneum of middle rectum o Women Pouch retrouterine Vagina o Men Retrovesicular pouch Fund of the bladder End parts of the ureters Vas deferens, seminal glands and prostate• Lateral o Pararectal fossa• Posterior o 3 lower sacral vertebrae o Coccyx o Anococcygeal ligament o Sacral vessels medial o Lower extremities of the sympathetic trunk and sacral plexusThe arterial supply of the proximal rectum is via the superior rectal artery from the inferior mesenteric artery1. The middle and lower rectum are irrigated by the middle rectal arteries which are branches of the internal iliac arteries1. The anorectal junction and the inferior anal canal are supplied by the inferior rectal artery from the internal pudendal artery1. The superior and inferior rectal arteries anastomose. Venous drainage flows via the upper, middle and lower rectal veins1. The superior and middle rectal veins drain into the terminating portal vein, while the inferior rectal vein drains...... middle of paper ...... the upper half of the anal canal drains deep into the lymph nodes internal iliacs, then in iliac nodes common to the lumbar lymph nodes1. The lower half drains superficially into the superficial inguinal lymph nodes1. The upper half of the anal canal has visceral innervation1. It is involuntary and is supplied by the hypogastric plexus with sympathetic, parasympathetic and visceral components that travel to S2-S41. The lower half has voluntary innervation with somatic innervation from the lower anal (rectal) nerves, which originate from the pudendal nerve1. This part of the canal is sensitive to pain, temperature and touch1.Works cited1. Moore KL, Dalley AF, Agur AMR. Clinically oriented anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2010. p.246-253; 411-414.2. Netter, FH. Atlas of Human Anatomy. 5th ed. Philadelphia: Saunders Elsevier; 2009. Plate 373.