Human anus

Human Anus

The human anus (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 defecation, which is the primary function of the anus. These are the internal anal sphincter and the external anal sphincter, which are circular muscles that normally maintain constriction of the orifice and which can be relaxed to allow ejection of feces from the body.

Anatomy

The human anus is situated between the buttocks, posterior to the perineum. It has a generally circular shape and is approximately 2-4 centimeters in diameter. The two sphincter muscles control the opening and closing of the anus; the internal anal sphincter is involuntary and the external anal sphincter is voluntary.

Physiology

The anus has a relatively high concentration of nerve endings, making it an area of sensitivity. It is involved in several significant bodily functions, including the expulsion of feces, the release of gas (flatulence), and the delivery of certain sexual responses.

Health and hygiene

Maintaining proper hygiene for the anus is important for overall health. Conditions such as hemorrhoids, anal fissures, rectal prolapse, and anal cancer can occur if proper care is not taken. Regular cleaning of the anus, along with the use of appropriate analgesics, can prevent these conditions.

Society and culture

In many societies, the anus is considered a taboo part of the body, and is often a subject of humor and innuendo. However, it also plays a role in certain sexual practices, such as anal sex and anilingus.

See also

• Digestive system
• Gastroenterology
• Proctology