sphincter

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sphincter

Anatomy a ring of muscle surrounding the opening of a hollow organ or body and contracting to close it
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Sphincter

 

a ringlike muscle that constricts to close a natural orifice such as the oral or anal opening, or to narrow the passage from one part of a hollow tubular organ to another, for example, from the stomach and bile duct to the duodenum and from the bladder to the urethra. The sphincter is always in a tonic state. The orbicular muscle of the iris is a sphincter. Some sphincters consist of striated muscle and others of smooth muscle innervated by the autonomic nervous system.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

sphincter

[′sfiŋk·tər]
(anatomy)
A muscle that surrounds and functions to close an orifice.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Anatomically, in women, the perineal body separates the anal canal from the urogenital diaphragm in the median plane where the deep bulbospongiosus and superficial transverse perineal muscles meet the external anal sphincter (EAS).
Clinically detectable anal sphincter injuries occur in about 0.4-19% of vaginal deliveries.
* Exposure of horizontal fibres of the internal anal sphincter (IAS).
For low fistulas involving <one-third of the sphincters, primary fistulotomy can be performed safely.
Several factors have been associated with persistent incontinence after MUS, including high preoperative pad weight, poor external sphincter coaptation on cystoscopy, and prior pelvic radiation or urethral surgery.
The following data were extracted: sphincter injury details, suture choice, repair technique, and details of surgeons performing the repair.
Obstetric Anal Sphincter injuries (OASI) occur in 0.5-9% of vaginal births.1 Women who have sustained OASI are more likely to suffer from faecal incontinence2 and OASI are responsible for significant physical, sexual and psychological sequelae.3 Women who have sustained OASI require more accurate, up to date information on the likelihood of developing faecal, urinary and sexual symptoms following primary repair.4 Therefore, accurate recognition and repair of anal laceration are of paramount importance in obstetric care.
There are numerous sphincters in the human body, including those that control the release of urine and faeces.
Far more frequently diagnosed non-neurogenic conditions include a weak internal urethral sphincter, bladder inflammation (cystitis); the formation of stones in the urinary tract (urolithiasis); and the development of benign or cancerous growths (neoplasms) in the tissue lining the bladder.