Human anus

External opening of the rectum

In humans, the anus (pl.: anuses or ani; from Latin ānus, "ring", "circle") 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.

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