Lateral Pharyngeal Diverticula

Abstract

True lateral pharyngeal diverticula occur only rarely, less than 20 such cases having been reported in the literature. In addition, and perhaps because of the infrequency of the condition, there is some confusion concerning the differentiation of acquired diverticula, congenital diverticula, simple localized bulging of the lateral pharyngeal walls, and pharyngo-celes. Therefore, we present three new cases, a practical classification (TABLE I), a brief account of the pertinent anatomy of the region, description of the radiographic appearance of the various types of lateral pharyngeal outpouchings, a review of the literature, and a discussion including clinical manifestations. We have found most useful the classification shown in TABLE I. Anatomy And Radiographic Technic A familiarity with the anatomy of the lateral oropharyngeal (mesopharyngeal) and hypopharyngeal walls is necessary for an appreciation of the various types of lateral pharyngeal protrusions. The lower portion of the oropharynx is separated from the hypopharynx by a fold of membrane, the pharyngo-epiglottic fold, which extends laterally from the outer margin of the base of the epiglottic tip to the lateral pharyngeal wall (Fig. 1, A). Above this fold, the lateral wall of the oropharynx is formed by the tonsillar fossa containing the palatine tonsil. The fossa wall consists of a thin fibrous sheath, continuous with the pharyngobasilar fascia and covered by two thin, flat muscle bundles, the palatopharyngeus and the superior constrictor. The flatness of the muscles in this region limits the intrinsic strength of the wall (4, 11). Below the pharyngo-epiglottic fold is the laryngo- or hypopharynx, the anterolateral compartments of which constitute the pyriform recesses. The lateral walls of these recesses are formed above by a fibrous sheath, the thyrohyoid membrane and ligament, which extends from the inferior margin of the hyoid bone to the superior margin of the thyroid cartilage on each side. Below, the lateral walls consist of the medial surfaces of the posterior portions of the thyroid cartilage lamina, covered by mucous membrane. Several muscles lie in close apposition to the thyrohyoid membrane and afford additional support to the lateral walls of the upper hypopharynx; these are the thyrohyoid anteriorly, the inferior constrictor postero-inferiorly and the middle constrictor pos-terosuperiorly. These muscles, however, fail to overlap completely so that a portion of the thyrohyoid membrane receives no muscular support (Fig. 2, A) (1, 4, 11, 17). Lateral to this unsupported “weak area” is only areolar tissue in which run the great vessels of the neck (Fig. 2, B).