Submucosal Elastic Laminae of the Middle and Lower Pharynx: A Histological Study Using Elderly Cadaveric Specimens

Abstract

Although the pharyngeal wall is well known to have high elasticity, the distribution of submucosal elastic fibers has not been described. Observations of histological sections of the mid and lower pharyngeal walls from 15 elderly donated cadavers were made. We found two distinct submucosal tissue layers with a high content of elastic fibers (tentatively termed the "submucosal elastic laminae"). The inferolateral elastic lamina was restricted to the level from the upper part of the arytenoid to the lower end of the inferior cornu of the thyroid cartilage. It originated from the pharyngeal submucosa, extended laterally along the inner aspect of the thyropharyngeal muscle, and inserted into the posterior margin of the thyroid cartilage including the cornu. The posteromedial lamina extended along the supero-inferior axis from a level above the greater horn of the hyoid bone to reach the muscularis mucosae of the cervical esophagus. The inferolateral and posteromedial laminae were connected at levels below the cricoarytenoid joint. Individual variations were evident in their thicknesses (ranging from almost absent to 0.3 mm) as well as the extent of connection between them. In association with striated muscle function, the inferolateral lamina seemed to suspend the lower pharyngeal mucosa, while the posteromedial lamina seemed to provide mucosal fold forcing smoothly peristaltic conveyance of a bolus during swallowing.