Fig. 1. The necessity of a bolus for activation of the esophageal phase of swallowing. This figure shows that under the same conditions and same stimulus when the bolus is diverted there is no change in the pharyngeal phase, but the esophageal phase is totally eliminated. The swallow was activated by water injection by pump into the pharynx through a catheter inserted 7 cm into the nasal cavity. The bolus was diverted by turning the arm of a 3 way stopcock that was inserted into the esophagus just caudal to the upper esophageal sphincter. ESO#, esophageal manometry recording # cm from the lower esophageal sphincter; GH, geniohyoideus; CP, cricopharyngeus; CT, cricothyroideus; EMG, electromyography. Adapted from Lang et al.
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