external anal sphincter


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ex·ter·nal a·nal sphinc·ter

[TA]
a fusiform ring of striated muscular fibers surrounding the anus, attached posteriorly to the coccyx and anteriorly to the central tendon of the perineum; it is subdivided, often indistinctly, into a subcutaneous part, a superficial part, and a deep part for descriptive purposes.
Farlex Partner Medical Dictionary © Farlex 2012
References in periodicals archive ?
Using EMG-biofeedback, the patients learned to relax external anal sphincter to permit defecation, decreasing significantly the anismus index.
In normal patients, any action that increases intra-abdominal pressure -- such as sneezing, coughing, rising from a chair, walking and even talking -- is always accompanied by compensatory increases in the activity of the external anal sphincter and puborectalis muscles.
Often, obstetricians try to ensure that the knots are buried within the body of the external anal sphincter muscle, rather than on the surface of the fascial sheath of the sphincter.
Table 1 : MRI scoring of External Anal Sphincter and Puborectalis Muscle Good SMC Age Group EAS (mm) PR (mm) 6m-3yrs 3 [+ or -] 0.2 3.1 [+ or -] 0.3 Upto 7 yrs 3.4 [+ or -] 0.3 3.8 [+ or -] 0.2 Upto 14 yrs 4.0 [+ or -] 0.4 4.7 [+ or -] 0.4 Fai/Moderate Poor/Severe Hypoplasia Hypoplasia Age Group EAS (mm) PR (mm) EAS (mm) PR (mm) 6m-3yrs 2-2.9 2.1-3.1 <2 <2.1 Upto 7 yrs 2.4-3.3 2.8-3.7 <2.4 <2.8 Upto 14 yrs 3-3.9 3.7-4.6 < 3 < 3.7 (EAS-external anal sphincter, PR-puborectalis) (Values mentioned under Good SMC are mean with standard deviation).
External anal sphincters (EAS), is 5mm thick and has of mixed echogenicity, with a white layer deficient anteriorly & superiorly.
The internal anal sphincter should be closed with the same fine interrupted or running sutures, and the external anal sphincter should be closed using 2-0 prolonged delayed absorbable (PDS/Maxon) sutures with either an overlapping or end-to-end technique.
Ultrasound identified anal sphincter defects in the external anal sphincter (61% of women), internal anal sphincter (3%), or both (36%).
For the external anal sphincter, use 2-0 prolonged delayed sutures (such as PDS II or Maxon), she advised, noting that second-degree repair and perineorrhaphy may be necessary to reattach the rectovaginal septum to the perineal body, thus restoring normal anatomy.
The external anal sphincter and puborectalis muscles reveal their tone as the patient squeezes.
The external anal sphincter is then mobilized and an overlapping repair is done.
Movement of feces out of the rectum is prevented by the internal and external anal sphincters and the pelvic floor muscles, particularly the pubo-rectalis muscle.
The lesion appeared to originate from between the internal and external anal sphincters, with the superior part of the lesion therefore lying in the intersphincteric plane and the lower part bulging out into the perineum.

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