What is the anatomy 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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Deglutition is the act of swallowing, which allows a food or liquid bolus to be transported from the mouth to the pharynx and esophagus, through which it enters the stomach. Normal deglutition is a smooth, coordinated process that involves a complex series of voluntary and involuntary neuromuscular contractions and typically is divided into distinct phases: oral, pharyngeal, and esophageal. Each stage facilitates a specific function; if the stages are impaired by a pathologic condition, specific symptoms may result.

The process of swallowing is organized with sensory input from receptors in the base of the tongue, as well as in the soft palate, faucial arches, tonsils, and posterior pharyngeal wall; this input is transmitted to the swallowing center, located within the pontine reticular system, through the facial (VII), glossopharyngeal (IX), and vagus (X) cranial nerves.

Information from the swallowing center then is conveyed back to the muscles that help in swallowing through trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), and hypoglossal (XII) cranial nerves, with the trigeminal, hypoglossal, and nucleus ambiguus constituting the efferent levels.

The act of swallowing usually interrupts the expiratory phase of ventilation, while the completion of expiration occurs when swallowing ends. In situations in which the swallowing is initiated during the inspiratory phase of ventilation, a brief expiration ensues after the completion of swallowing.

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