Normal erect swallowing normal function and incidence of variations

Of 871 candidates presenting for upper gastrointestinal examinations, 16 met the rigorous criteria established for selecting asymptomatic normal volunteers. Frame-by-frame evaluation of their videorecorded pharyngeal swallow confirmed many observations made previously utilizing cine recording at much higher radiation dosages. In addition, new observations were made: (1) the nasopharynx may not occlude until the bolus is entirely within the pharynx; (2) air mixes with the bolus if the swallow is an “open” type; (3) the epiglottis always inverts in normal individuals regardless of the type of swallow (“open,” air filled oro- and hy popharynx into which the swallowed bolus is dropped; “closed,” airless oropharynx into which the swallowed bolus is pushed by a continuous peristaltic drive of the tongue and palate, thus reconstituting the pharyngeal space); (4) laryngeal descent may aid in stripping the bolus from the pharynx; (5) the vestibule may not completely close during the swallow and the larynx can still be impervious to the bolus; (6) the peristaltic wave does not begin until the bolus has breeched the cricopharyngeus; (7) the cricopharyngeus may be seen frequently in normal individuals, but does not delay the passage of the bolus; (8) asymmetric flow of the bolus around the positioning.