Safe swallowing of solid foods and liquids is the result of a complex interaction of cranial nerves and muscles of the oral cavity, pharynx, and proximal esophagus. During the voluntary oral phase, the food bolus is altered in the mouth and propelled past the pharynx where the respiratory and gastrointestinal tracts meet; precise coordinating mechanisms are crucial to prevent aspiration into the respiratory passage. Normal mechanisms of safe swallow include raising of the palate, epiglottic tilt, cord closure, primary peristalsis of the esophagus, and the tone and sequential relaxation of the upper and lower esophageal sphincters. Disorders affecting the central and peripheral nervous system and muscles of the previously noted structures, therefore, can affect swallowing mechanisms and lead to potentially dangerous sequelae.

Aspiration may be defined as the accidental entry of a foreign substance into the respiratory tract. The consequences may be devastating, chronic, or subtle, ranging from sudden death...

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