The cricopharyngeal muscle works as the upper esophageal sphincter in deglutition. In the intraluminal manometric study, high resting pressure at the pharyngo-esophageal junction (PEJ) falls to the atmospheric pressure on swallowing, but the mechanism of this pressure change is not fully clarified. Using three mongrel dogs, the authors investigated that me-chanism by the simultaneous recordings of the laryngeal movement, the intraluminal pressure and the electromyograms of the thyrohyoid, thyropharyngeal and cricopharyngeal muscles.
As a result, the resting pressure at the PEJ fell before the onset of the elevation of the larynx in every swallowing and the relaxation of the cricopharyngeal muscle started prior to the falling of the resting pressure at the PEJ. On the basis of the results, the authors concluded that the drop in pressure at the PEJ during swallowing was mainly caused by the relaxation of the cricopharyngeal muscle.
