pharynx, area of the gastrointestinal and respiratory tracts which lies between the mouth and the esophagus. In humans, the pharynx is a cone-shaped tube about 41/2 in. (11.43 cm) long. At its upper end, it is continuous with the mouth and nasal passages, and connects with the ears via the Eustachian tubes. The lower end of the pharynx is continuous with the esophagus (see digestive system). It is also connected to the larynx by an opening that is covered by the epiglottis during swallowing, thus preventing food from entering the trachea. The pharyngeal area is the embryological source of several important structures in vertebrates. For example, the breathing apparatus (gill pouches of fish and lungs of land animals) arises in this area (see respiration). In humans, the pharynx is particularly important as an instrument of speech: it functions with the various parts of the mouth to articulate the initial sounds produced in the larynx.

Inside of the throat, from the oral and nasal cavities (see mouth, nose) to the trachea and esophagus. It has three connected sections: the nasopharynx, at the back of the nasal cavity; the oropharynx, in the back of the oral cavity down to the epiglottis (a flap of tissue that closes off the larynx during swallowing); and the laryngopharynx, from the epiglottis to the esophagus. The oropharynx contains the palatine tonsils. The eustachian tubes connect the middle ears to the pharynx, allowing air pressure on the eardrum to be equalized. Disorders include pharyngitis, tonsillitis, and cancer.

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