The rectum and anus

At the level of the middle of the sacrum, the sigmoid colon loses its mesentery and gradually becomes the rectum, which, at the upper limit of the pelvic diaphragm, ends in the anal canal fig. The rectum, about 15 cm long, widens below as the ampulla, which is very distensible. Although variable in shape, the rectum follows the sacrococcygeal curve. At the anorectal junction, the gut curves backward and its concavity is held by the puborectal sling, which can be palpated per anum. The rectum presents three or more lateral curvatures, which correspond to transverse rectal folds in the interior of the gut. The rectum has neither mesentery nor haustra, and it has an almost complete outer longitudinal muscular coat rather than teniae. In the upper third of the rectum, its front and sides are covered by peritoneum; in its middle third, the front only; its lower third is devoid of peritoneum.

The rectum is the concluding part of the large intestine that terminates in the anus. The average length of the human rectum may range between 10 and 15 cm. Its diameter can be compared to that of the sigmoid colon the part of the large intestine nearest the rectum at its onset. However, it becomes larger near the anus, where it forms the rectal ampulla. The key role of the rectal ampulla is to act as a temporary storehouse for feces. The expansion of the rectal walls causes the stretch receptors within the walls to stimulate the urge to defecate.

The rectum is the concluding part of the large intestine that terminates in the anus. The average length of the human rectum may range between 10 and 15 cm. Its diameter can be compared to that of the sigmoid colon the part of the large intestine nearest the rectum at its onset. However, it becomes larger near the anus, where it forms the rectal ampulla.

The rectum and anus are the final stages of the digestive tract. The rectum is the last straight section of the large intestine before reaching the anus. The anus is the opening at the lower end of the digestive tract that controls the expulsion of feces. Read on to learn more about the rectum and anus, and their role in digestion.