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Related to Upper esophageal sphincter: lower esophageal 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 It might be outdated or ideologically biased.



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.


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 ?
Abbreviations: ASHA = American Speech-Language-Hearing Association, BOT = base of the tongue, ES = effect size, N-CEP = National Center for Evidence-Based Practice in Communication Disorders, PPW = posterior pharyngeal wall, SM = submental, UES = upper esophageal sphincter, VA = Department of Veterans Affairs.
Manometry of the upper esophageal sphincter revealed a high resting pressure (160 mm Hg) with poor relaxation (residual pressure: 20 mm Hg).
(4) They proposed other potential mechanisms, including (1) functional derangement of the upper esophageal sphincter secondary to the pressure of the endotracheal tube cuff and (2) the use of drugs that impair esophageal motility.
To document the presence of acid in the pharynx of presumed LPR patients, Wiener et al used both an esophageal pH probe and a pH probe placed in the pharynx just above the upper esophageal sphincter. (21) Patients actually wore two pH boxes, and the two pH probes were piggy-backed together with small dental rubber bands.
(1,7) It is believed that the primary defect in GERD is lower esophageal dysfunction, whereas the primary defect in LPR might be upper esophageal sphincter dysfunction.
Similarly, using esophageal pH data (even at a proximal esophageal location) to prove the presence or absence of LPR is invalid, because the upper esophageal sphincter (UES) functions as the final barrier against LPR.
(30) The proximal probe must be placed just above the upper esophageal sphincter in the hypopharynx.
Several authors have reported that the upper esophageal sphincter is a difficult area to examine with a flexible esophagoscope.

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