耳管の液体排泄作用に関する実験的研究

抄録

To determine the muscles responsible for the pumping function of the Eustachian tube and to examine the detailed processes of this function, 1) a measurement of the intratympanic pressure during swallowing and during electrical stimulation of the tensor veli palatini muscle (TVPM) and of the levator veli palatini muscle (LVPM), 2) microscopic and radiographic observations of fluid movement through the tube in open middle ear cavity, and 3) endoscopic observation of fluid clearance in closed middle ear cavity, were conducted in dogs, cats, and a monkey.
The results were, 1) pressure drop in dilated tube by TVPM contraction, 2) displacement of the fluid from the tympanum into the tube by the negative pressure, and 3) expulsion of the fluid out of the tube to the pharynx by TVPM relaxation and tubal closure. It was concluded that TVPM contractions and relaxations cause the pumping-like function of the tube, which expells any fluid from the tympanum into the pharynx. However, it was also suggested that ventilatory function of the tube might be indispensable for fluid clearance in the closed middle ear cavity.
To investigate the significance of the tensor tympani muscle (TTM) in tubal functions, 1) electromyographic and microscopic observation of TTM contraction, 2) a measurement of the intratympanic pressure both during independent TTM contraction and during combined contraction of TVPM and TTM, were conducted in cats. The results were 1) TTM contraction during swallowing did not result in any change of middle ear pressure. 2) TTM contraction by acoustic stimulation consistently raised middle ear pressure, but it failed to enhance the TVPM contraction for opening of the tube. It was concluded that TTM does not play any role in tubal functions.