Mechanism and timing of nasopharyngeal closure during swallowing and belching. Dua, Kulwinder, Reza Shaker, Junlong Ren, Ronald Arndorfer, Candy Hofmann. MCW Dysphagia Institute, Medical College of Wisconsin and VA Medical Center, Milwaukee, WI.
APStracts 2:0037G, 1995.
Mechanism(s) of nasopharyngeal closure and its temporal relationship with other biomechanical events during swallowing and belching was studied in seven healthy volunteers, age 26 to 39 yrs, by concurrent videoendoscopic, videofluoroscopic, and manometric technique. Analysis of the videoendoscopic recordings showed that deglutitive nasopharyngeal closureconsisted of elevation of the soft palate and adduction of the superior pharyngeal constrictor muscle. Videofluoroscopy identified only the palatal elevation clearly. During belching, however, only palatal elevation occurred. Deglutitive nasopharyngeal closure ranged between 0.73 to 0.94 seconds (0.8+/-0.04 SEs) with a tendency to be longer with larger swallowed volumes. Onset of nasopharyngeal closure was identified earlier endoscopically than as seen fluoroscopically. Complete nasopharyngeal closure preceded the arrival of barium bolus into the pharynx and this pattern was seen for all volumes tested. Manometric onset of UES relaxation was seen before the onset of nasopharyngeal closure but the physical opening of the UES as seen fluoroscopically occurred after complete closure of the nasopharynx. Conclusions: 1) Mechanism of nasopharyngeal closure during swallowing and belching is different; during swallowing, nasopharyngeal closure has two tiers of closure: palatal elevation and superior pharyngeal muscle adduction; during belching only palatal elevation occurs; 2) nasopharyngeal closure is tightly coordinated with other biomechanical events, during swallowing and belching. 

Received 9 August 1994; accepted in final form 30 January 1995.
APS Manuscript Number G308-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.