Food that has been ingested and chewed then passes into the pharynx, a common passageway for food and air.
Several structures open into the pharynx. They include the mouth, the nasal cavity, the larynx, the esophagus, and
the eustachian tubes from the ears. The pharyngeal muscles of the pharynx force food into the esophagus from the
mouth. The eustachian tubes allow air to move freely from the pharynx to the eardrum (tympanic membrane). This
allows the pressure to equalize on either side of the eardrum. The muscles contract in a series, from the top to the
bottom end of the pharynx, during swallowing. This shortens the pharynx and pushes the food into the esophagus