Descriptive anatomy of the human auditory tube.

Abstract

The aim of this study was to correlate current morphologic data relating to the lumen of the auditory tube. Four methods were used: dissection under the operating microscope; microendoscopy of the tubal lumen; optical and electron microscope histology; and MR or CT imaging. The auditory tube consists of two unequal cones, a small posterior third, fixed and osseous (protympanum), and a mobile fibrocartilaginous anterior two-thirds, both joined by the tubal isthmus, a short constriction which is pseudosphincteric at endoscopy. The tensor veli palatini muscle (TVPM) and the levator veli palatini muscle (LVPM) are the chief muscles that vary the tubal lumen of the fibrocartilaginous portion, which is collapsed at rest. CT and especially MR imaging allows their observation in static conditions. Serial histologic sections reveal the continuity between the TVPM and the tensor tympani muscle. The main cartilage framing the lumen varies in shape according to the level surveyed. The tubal mucosa is lined with an epithelium combining ciliated and mucus cells, involved in mucociliary drainage and gas exchanges in the auditory tube. These morphologic elements represent a basis for study of tubal physiology and for planning treatment in dysfunctions of the auditory tube.