Human anus

Human anus
The anus of a female with a prominent perineal raphe (left) and a male with anal pubic hair (right)
Scheme of digestive tract, with anus marked
Details
Precursor	Proctodeum
System	Alimentary
Artery	Inferior rectal artery
Vein	Inferior rectal vein
Nerve	Inferior rectal nerves, pudendal nerve
Lymph	Superficial inguinal lymph nodes
Identifiers
Latin	anus
TA98	A05.7.05.013
TA2	3022
FMA	15711
Anatomical terminology [edit on Wikidata]

Major parts of the
Gastrointestinal tract
Upper gastrointestinal tract Mouth Pharynx Esophagus Stomach Duodenum
Lower gastrointestinal tract Small intestine Jejunum Ileum Large intestine Cecum Appendix Ascending colon Transverse colon Descending colon Sigmoid colon Rectum Anus
See also Gastrointestinal wall Human digestive system Anatomical terminology Outline of anatomy
v t e

In humans, the anus (pl.: anuses or ani; from Latin ānus, "ring", "circle")^[1][2] is the external opening of the rectum located inside the intergluteal cleft. 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 relax as required by normal physiological functioning. The inner sphincter is involuntary and the outer is voluntary. Above the anus is the perineum, which is also located beneath the vulva or scrotum.

In part owing to its exposure to feces, a number of medical conditions may affect the anus, such as hemorrhoids.^[3] The anus is the site of potential infections and other conditions, including cancer (see anal cancer).^[4]

With anal sex, the anus can play a role in sexuality. Attitudes toward anal sex vary, and it is illegal in some countries.^[5] The anus is often considered a taboo part of the body,^[5] and is known by many, usually vulgar, slang terms. Some sexually transmitted infections including HIV/AIDS and anal warts can be spread via anal sex.