Velar activity and timing of eustachian tube function in swallowing.

Abstract

Velar motion for dry and liquid swallows was investigated. as well as velar activity in speech, based on X-ray microbeam pellet tracking data. Electromyographic recordings for tensor and levator veli palatini were obtained simultaneously. Velar pellet trajectories for swallowing were more complex than for speech, since there was a high-velocity anterior component in swallowing. For some swallows this anterior component was integrated with velar elevation (especially in liquid swallows), but in other cases initial velar elevation occurred considerably earlier (chiefly in dry swallows). The burst of tensor and levator veli palatini activity characteristic of swallowing was associated with the anterior component of velar pellet motion, but not consistently with velar elevation per se. The conventional view on timing of tensor veli palatini contraction in a swallow, which governs Eustachian tube opening, is that this is associated with velar closure. The X-ray microbeam data suggest rather that Eustachian tube ventilation is more closely associated in time to the onset of pharyngeal peristalsis, which may or may not coincide with initial velar elevation.