Inflammation of the pharynx is termed pharyngitis, regardless of the etiology. The pharynx is a fibromuscular tube connecting the nose and the oral cavity from above to the larynx and esophagus below. The pharynx functions as a conduit and is shared by the respiratory and digestive tracts. It is divided into three anatomic substructures: the nasopharynx, the oropharynx, and the hypopharynx.
The nasopharynx begins anteriorly at the choana with its superior limit at the skull base and the inferior limit at the soft palate. The adenoids are an aggregation of lymphoid tissue located on the posterior wall of the nasopharynx between the openings of the Eustachian tubes laterally (Fig. 1). Gerlach's tonsils are an aggregate of lymphoid tissue adjacent to the Eustachian tube openings. The anterior extent of the oropharynx is the glossopalatine arch, also termed the anterior tonsillar pillar. The superior limit of the oropharynx is the soft palate and the inferior limit is the tongue base. The palatine tonsils lie in a triangular space formed by the glossopalatine arch anteriorly and the pharyngopalatine arch posteriorly. The lingual tonsils are located on the posterior tongue base. Waldeyer' s ring is the lymphatic tissue network composed of the adenoids, Gerlach' s tonsils, palatine tonsils, and lingual tonsils. The hypopharynx is the segment of the upper aerodigestive tract that lies between the oropharynx superiorly and the esophagus and larynx inferiorly. The substructures of the hypopharynx are the postcricoid area anteriorly, the paired pyriform sinuses laterally, and the posterior pharyngeal wall.
The normal mucosal lining of the nasopharynx is ciliated pseudostratified respiratory epithelium. The oropharynx and hypopharynx are lined by a nonkeratinizing, stratified squamous epithelium. The mucosa and submucosa of the pharynx covers the superior, middle, and inferior constrictor muscles that represent the major muscular structures of the pharynx. Other minor muscles in the pharynx are the palatopharyngeus, the salpingophar-yngeus, and the stylopharyngeus, as well as muscles of the soft palate. The pharynx is innervated by the pharyngeal plexus derived from CN IX and CN X.
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