3 Anatomy of Swallowing

Successful swallowing is accomplished through the actions of over 29 muscles and the interaction of multiple oropharyngeal structures. Food or liquid is placed in the oral cavity and the bolus is prepared. In the case of solid foods, mastication is required; however, thin liquids can pass quickly from the front to the back of the oral cavity. Once in the posterior oral cavity, the bolus is transported into the pharynx.

The pharyngeal cavity provides a conduit for passage of the prepared bolus from the mouth to the food tube (esophagus) while discouraging penetration into the nearby nasal or airway entrances. Once the food passes through the gate between the pharynx and the esophagus (a.k.a. the pharyngo-esophageal segment or the upper esophageal sphincter region), the bolus is propelled downward through the esophagus toward the stomach. The movie in Box 1.1 highlights the oral and pharyngeal structures of importance to swallowing in a healthy adult through use of a lateral x-ray. Pediatric structures, while similar, are arranged in a somewhat different proximity (smaller more compact structure) and will be discussed later in this section.