The rectum is the final straight portion of the large intestine in humans and some other mammals , and 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 line , again depending upon which definition is used. The word rectum comes from the Latin rectum intestinum , meaning straight intestine. The rectum is a part of the lower gastrointestinal tract. The rectum is a continuation of the sigmoid colon , and connects to the anus.
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 glands make mucus, which acts as a lubricating fluid. Anal cancers that start from cells in the glands are called adenocarcinomas. Anal cancers are often divided into 2 groups, which are sometimes treated differently:.
The anal canal is located within the anal triangle of the perineum between the right and left ischioanal fossae. It is the final segment of the gastrointestinal tract, around 4cm in length. The canal begins as a continuation of the rectum , and passes inferoposteriorly to terminate at the anus. Except during defecation, the anal canal is collapsed by the internal and external anal sphincters to prevent the passage of faecal material. It is formed by the fusion of the internal anal sphincter, external anal sphincter and puborectalis muscle, and is palpable on digital rectal examination.
The anal canal is the terminal segment of the large intestine between the rectum and anus , located below the level of the pelvic diaphragm. It is located within the anal triangle of perineum , between the right and left ischioanal fossa. As the final functional segment of the bowel, it functions to regulate release of excrement by two muscular sphincter complexes.