Skip to Content

internal anal sphincter

 

Definition: a smooth muscle ring, formed by an increase of the circular muscle fibers 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 fecal mass. It is inhibited with filling of the ampulla, increased distension, and peristalsis.

Synonym(s): musculus sphincter ani internusTA, internal sphincter muscle of anus

Disclaimer: This site is designed to offer information for general educational purposes only. The health information furnished on this site and the interactive responses are not intended to be professional advice and are not intended to replace personal consultation with a qualified physician, pharmacist, or other healthcare professional. You must always seek the advice of a professional for questions related to a disease, disease symptoms, and appropriate therapeutic treatments.
© Copyright 2017 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.
Hide