Pharyngeal phase

The pharyngeal phase is the part of swallowing that moves a food or liquid bolus through the pharynx, or throat, toward the esophagus. It follows the oral phase, in which the bolus is prepared and moved backward from the mouth, and precedes the esophageal phase, which carries the bolus through the esophagus toward the stomach .¹

During the pharyngeal phase, a rapid, coordinated sequence of muscle movements both propels the bolus and protects the airway. The soft palate elevates to limit entry into the nasal cavity, the tongue base and pharyngeal muscles help drive the bolus downward, and the larynx elevates while the airway closes. At the same time, the upper esophageal sphincter relaxes and opens, allowing the bolus to enter the esophagus. Breathing is normally interrupted briefly during this sequence .^1,2

The motor pattern of the pharyngeal phase is organized largely by neural circuits in the brainstem and is strongly influenced by sensory information from the mouth and pharynx. Although traditionally described as a reflexive phase of swallowing, it is not completely inflexible or independent of higher brain control. Sensory input and signals from higher brain regions can modify the timing and pattern of the response .^1,2

The oral, pharyngeal, and esophageal phases are useful functional divisions, but swallowing operates as a coordinated, continuous process. The transition from pharyngeal swallowing to esophageal transport is closely coordinated .^1,3