AJP - Gastrointestinal and Liver Physiology, Vol 268, Issue 6 1037-G1042, Copyright © 1995 by American Physiological Society
Mechanism and timing of nasopharyngeal closure during swallowing and belching
K. Dua, R. Shaker, J. Ren, R. Arndorfer and C. Hofmann
Medical College of Wisconsin Dysphagia Institute, Milwaukee, USA.
The mechanism(s) of nasopharyngeal closure (NPC) and its temporal
relationship with other biomechanical events during swallowing and belching
were studied in seven healthy volunteers, aged 26-39 yr, by concurrent
videoendoscopic, videofluoroscopic, and manometric technique. Analysis of
the videoendoscopic recordings showed that deglutitive NPC consisted 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 NPC ranged between 0.73 and 0.94 s (0.8 +/- 0.04 SE), with a
tendency to be longer with larger swallowed volumes. Onset of NPC was
identified earlier endoscopically than as seen fluoroscopically. Complete
NPC preceded the arrival of barium bolus into the pharynx, and this pattern
was seen for all volumes tested. Manometric onset of upper esophageal
sphincter (UES) relaxation was seen before the onset of NPC, but the
physical opening of the UES as seen fluoroscopically occurred after
complete closure of the nasopharynx. We conclude the following: 1) The
mechanism of NPC during swallowing and belching is different. During
swallowing, NPC has two tiers of closure, palatal elevation and superior
pharyngeal muscle adduction; during belching only palatal elevation occurs.
2) NPC is tightly coordinated with other biomechanical events during
swallowing and belching.
