See Also: internal sphincter muscle of anus(medicine)
external sphincter muscle of anus(medicine)
elevator muscle of anus(medicine)
corrugator cutis muscle of anus(medicine)
internal anal sphincter(medicine)
internal urethral sphincter(medicine)
Internal Medicine(health)
internal medicine(medicine)
internal medicine(encyclopedia)
internal medicine(dictionary)

internal sphincter muscle of anus (medicine)


internal sphincter muscle of anus -->
internal anal sphincter
<anatomy> A smooth muscle ring, formed by an increase of the circular fibres of the rectum, situated at the upper end of the anal canal, internal to the outer voluntary external anal sphincter.

This sphincter is maximally-contracted when the rectal ampulla is at rest -empty or relaxed to accommodate a distending faecal mass. It is inhibited with filling of the ampulla, increased distension and peristalsis.

Synonym: musculus sphincter ani internus, internal sphincter muscle of anus.