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1 Anatomy and function of the human anus

The human anus is situated between the buttocks, posterior to the perineum. It has two anal sphincter s, one internal, the other external. These hold the anus closed until the body is ready to defecate.

When the rectum is full the increase in intrarectal pressure forces the walls of the anal canal apart allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic waves propel the feces out of the rectum. The internal and external sphincters of the anus allow the feces to be passed by muscles pulling the anus up over the exiting feces.

In some contexts, the anus is considered a sex organ because it contains erotically pleasurable nerve endings. (See: anal sex, anilingus (rimming).)

2 Anal pathologies

• Anal fissure
• Hemorrhoids
• Anal cancer
• Fecal incontinence
• Anal fistula
• Anal abscess es

3 See also

• enemaAn enema (plural enemata or enemas is the procedure of introducing liquids into the bowel via the anus. Enemas can be carried out for medical reasons, as part of alternative therapies, and also for erotic purposes, particluarly as part of BDSM activities.
• cloacaIn zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, urinary, and genital tracts of certain animal species. All birds, reptiles, and amphibians possess this orifice, by which they simultaneously
• suppositoryA suppository is a medicine that is inserted either into the rectum (rectal suppository) or into the vagina (vaginal suppository) where it melts. Vaginal suppositories are used to treat gynaecological ailments, especially vaginal infections such as candid
• flatulenceFlatulence consists of gases that are produced by symbiotic bacteria and yeasts living in the gastrointestinal tract of mammals and are released through the anus. Flatulence is known colloquially as farting . The primary constituents of flatulence (collec