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 12 cm. Its caliber can be compared to that of the sigmoid colon at its onset. However, it gets dilated near the anus, where it forms the rectal ampulla. Its key role 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. If the defecation process is delayed, it may result in constipation. When the storage site becomes full, the intrarectal pressure causes the anal canal walls to pull apart. This results in the feces entering the canal. A rectal exam may be conducted to diagnose certain diseases. Certain types of cancers may be diagnosed by performing an endoscopy in the rectum. Body temperature may also be obtained from the rectal area. In case of infants and babies, it can be a more accurate method to measure body temperature.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Rectum