Abstract
The degree of opening and closing of the eustachian tube varied with changes in body position. However, neither the duration of auditory tube opening and closing nor the opening pressure varied.
The physiological reason for such findings appears to involve the anatomic course of the pharyngeal orifice of the auditory tube and of the auditory tube itself, protecting the middle ear cavity from invasion by secretions and from infections. When a patient with mild dysfunction of the auditory tube lies on his side, the middle ear cavity pressure becomes markedly positive. Involvement of congestion in the venous plexus of the middle ear cavity and of gas emission is suggested in this shifting of tympanic compliance to the positive pressure side with change in head position or when lying on the side. These findings, show that the ventilation of the middle ear cavity under environmental pressure, keeping the internal pressure of the middle ear cavity equal or slightly higher than atmospheric pressure at all times, serves to maintain the conductive efficiency of the middle ear cavity through adjusting of the internal pressure of the middle ear cavity to atmospheric pressure by the opening and closing of the auditory tube.
