The human Eustachian tube is known to open and close with spontaneous swallowing, providing ventilation of the tympanic cavity and mastoid cells. There have been few reports on the relationship between movement of the soft palate and opening/closing of the Eustachian tube with swallowing. This paper presents a study of this relationship by combining sonotubometry and fluoroscopy of the soft palate.
During swallowing, the soft palate is raised rapidly posterior-superiorly to close the rhinopharynx. When the soft palate reaches a maximum level, or slightly thereafter, the Eustachian tube opens.
Observations of the opening and closing ability of the Eustachian tube and soft palate movement during swallowing of saliva revealed a positive sonotubometric pattern in 80% of 40 ears of 20 healthy adult males. This pattern was positive in 65% of 40 ears of 20 healthy females during swallowing of liquid and in 77.5% during residual swallowing.
Differences in the movement of the soft palate were examined by Toynbee's method during the swallowing of liquid and of saliva, and changes in intranasal pressure and sonotubometry were recorded simultaneously. The soft palate rose higher when liquid was swallowed than when saliva was swallowed, but after the swallowing of liquid it resumed its original state more slowly. There was also a slight difference in the timing of opening and closing of the Eustachian tube: it opened during the swallowing of saliva and closed after the intranasal pressure became negative, but during the swallowing of liquid it tended to close while the intranasal pressure was still positive.
The above results led to the following conclusions: the movement of the soft palate varies with the swallowing pattern, and causes slight differences in the opening and closing ability and timing of the Eustachian tube.
Finally, the author discusses the mechanism of Eustachian tube dysfunction in cases of adenoid hypertrophy from the stand point of inhibited movement of the soft palate.
