The human anus from 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 defecationwhich is the primary function of the anus.
These are the internal anal sphincter and the external anal sphincterwhich are circular muscles that normally maintain constriction of the orifice and which relaxes as required by normal physiological functioning. The inner sphincter is involuntary and the outer is voluntary.
It is located behind the perineum which is located behind the vagina in females and for the scrotum in males. With anal sexthe anus can men a role in sexuality.
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Attitudes towards anal sex vary and it is illegal in men countries. The anus is also the site of potential infections and other conditions, including cancer. The anus is the final component of the gastrointestinal tractand directly continues from the rectum.
The anus passes through the pelvic floor. The anus is surrounded by muscles. The top and bottom of the anus are surrounded by the internal and external anal sphincterstwo muscular rings which control defecation. The anus is surrounded in its length by folds called anal valves, which converge at a line for as the pectinate line.
Anus represents the point of transition between the hindgut and the ectoderm in the embryo.