Rectal prolapse occurs when the rectum the last section of the large intestine falls from its normal position within the pelvic area and sticks out through the anus. The word "prolapse" means a falling down or slipping of a body part from its usual position. Rectal prolapse is common in older adults who have a long-term history of constipation or a weakness in the pelvic floor muscles.
The human anus from Latin anus meaning "ring", "circle"   is the external opening of the rectum. Two sphincters control the exit of feces from the body during an act of defecationwhich is the primary function of the anus. These are the internal anal sphincter and the external anal sphincterwhich are circular muscles that normally maintain constriction of the orifice and which relaxes as required by normal physiological functioning.
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.
The rectum is the final straight portion of the large intestine in humans and some other mammalsand the gut in others. The adult human rectum is about 12 centimetres 4. It terminates at the level of the anorectal ring the level of the puborectalis sling or the dentate lineagain depending upon which definition is used.
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The inner lining of the anal canal is the mucosa. Most anal cancers start from cells in the mucosa. Glands and ducts tubes leading from the glands are found under the mucosa.
The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus see also Overview of the Anus and Rectum. Ordinarily, the rectum is empty because stool is stored higher in the descending colon. Eventually, the descending colon becomes full, and stool passes into the rectum, causing an urge to move the bowels defecate. Adults and older children can withstand this urge until they reach a bathroom.
The anus is the opening at the end of the digestive tract where stool leaves the body. The rectum is the section of the digestive tract above the anus where stool is held before it passes out of the body through the anus. The anus is formed partly from the surface layers of the body, including the skin, and partly from the intestine.