Localization of function in the eustachian tube: a hypothesis.

This communication uses our recent quantitative morphometric studies to develop a hypothesis for localization of ventilatory, clearance, and protective functions in different portions of the eustachian tube (ET). We hypothesize that the ET roof is involved mainly with ventilation and that the ET floor is involved mainly with clearance, whereas both portions are involved with protection of the middle ear. The hypothesis states that 1) the cross-sectional shape of the ET lumen and the attachment of the tensor veli palatini muscle to the tip of the lateral lamina are important for ventilation, 2) the ciliated cells in the ET floor subserve clearance, 3) the richly distributed elastin in the hinge portion of the ET cartilage, Ostmann's fatty tissue, and rich mucosa-associated lymphoid tissue are protective, 4) the well-developed ET cartilage lateral lamina is important for both ventilation and protection, and 5) the rich mucosal folding, goblet cells, and glands subserve both clearance and protection. Finally, the utility of the hypothesis for elucidating anatomic factors in otitis media is discussed.