internal anal sphincter

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in·ter·nal a·nal sphinc·ter

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.
Farlex Partner Medical Dictionary © Farlex 2012

internal anal sphincter

A muscular ring surrounding the lower end of the rectum.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
Endosonographic variations in the normal internal anal sphincter. Int J Colorectal Dis.
* Women with injuries to the internal anal sphincter or rectal mucosa have a worse prognosis for future continence problems (A).
The pain at the beginning of the process is due to the spasm in the external and internal anal sphincter caused by foreign bodies stuck in the anal canal but then the abscess formation around the foreign body, which is pushed out of the wall of the anal canal.
The internal anal sphincter; its surgical importance.
Repair the internal anal sphincter with a 3-0 suture on a tapered needle
However, topical diltiazem can be prescribed as first line of management since it is non-invasive and is free of complications associated with surgical division of internal anal sphincter.
Notably, the function and morphology of the internal anal sphincter, which have a direct bearing on anal continence, are not typically affected by PPH.
Plicate the internal anal sphincter. Perform an overlapping external anal sphincteroplasty, if indicated.
It's not for everyone with fecal incontinence, however, as it requires intact internal anal sphincter muscles, said Dr.
* Third Degree (Injury to the anal sphincter complex: 3a = < 50% of the external anal sphincter torn 3b = 50% of the external anal sphincter torn 3c = Injury to the external and internal anal sphincter); and
It is also important to recognise that the defect invariably extends into the internal anal sphincter, and often into the external anal sphincter as well.

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