What are processes in the pharyngeal phase of swallowing relevant to dysphagia?

Updated: Mar 20, 2020
  • Author: Nam-Jong Paik, MD, PhD; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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Answer

The pharyngeal phase is of particular importance, because without intact laryngeal protective mechanisms, aspiration (the passage of food or liquid through the vocal folds) is most likely to occur during this phase. This phase involves a rapid sequence of overlapping events. The soft palate rises, the hyoid bone and larynx move upward and forward, the vocal folds move to the midline, the epiglottis folds backward to protect the airway, and the tongue pushes backward and downward into the pharynx to propel the bolus downward. [9] The tongue is assisted by the pharyngeal walls, which move inward with a progressive wave of contraction from top to bottom.

The upper esophageal sphincter relaxes during the pharyngeal phase of swallowing and is pulled open by the forward movement of the hyoid bone and larynx. This sphincter closes after passage of the food, and the pharyngeal structures then return to the reference position. (See the image below.)

Pharyngeal phase of normal swallowing. Pharyngeal phase of normal swallowing.

The pharyngeal phase of swallowing is involuntary and totally reflexive, so no pharyngeal activity occurs until the swallowing reflex is triggered. This swallowing reflex lasts approximately 1 second and involves the motor and sensory tracts from cranial nerves IX (glossopharyngeal) and X (vagus).


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