anus /ā′nəs/
noun
The opening at the lower end of the digestive tract through which solid waste is eliminated from the body.
The posterior opening of the alimentary canal, through which the excrements are expelled.
The lower opening of the alimentary canal, through which feces and flatus are ejected.
In humans, the anus 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.
Precursor Proctodeum
System Alimentary
Artery Inferior rectal artery
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