oropharynx

The oropharynx is the middle part of the pharynx, located behind the oral cavity and extending from the soft palate to the superior border of the epiglottis. It communicates with the oral cavity through the oropharyngeal isthmus, and is bounded laterally by the palatoglossal and palatopharyngeal arches, with the posterior wall forming its back boundary. The superior boundary is the soft palate and the inferior boundary is the upper edge of the epiglottis.

The mucosa of the oropharynx is lined mainly by non-keratinized stratified squamous epithelium, adapted to contact with ingested material. The region contains lymphoid tissue forming part of Waldeyer's ring, including the palatine tonsils in the tonsillar fossae between the palatoglossal and palatopharyngeal arches, and the lingual tonsils on the posterior tongue. The pharyngeal constrictor muscles contribute to the lateral and posterior walls and aid in swallowing.

Innervation of the oropharynx involves a pharyngeal plexus with contributions from the glossopharyngeal nerve (CN IX) and the vagus nerve (CN X). Sensation from the oropharynx and taste from the posterior third of the tongue are primarily via CN IX. Motor control of the pharyngeal phase of swallowing is mainly via CN X, with the stylopharyngeus supplied by CN IX.

Functionally, the oropharynx serves in swallowing, moving the bolus from the mouth into the laryngopharynx and esophagus while helping protect the airway. It also participates in immune defense through the lymphoid tissue of Waldeyer's ring. Clinically, it is a common site for tonsillitis and for oropharyngeal cancer, with risk factors including HPV infection and tobacco use.