It is an established fact that the eustachian tube plays a major part in protecting the middle ear from nasopharyngeal pathologic influences. On the other hand, when the eustachian tube is not functioning normally, it becomes a contributing factor to impairment of the middle ear. After four years of uninterrupted observation on the pathology of the eustachian tube, there are a few personal observations I should like to add to the literature on this subject.
The eustachian tube is the chief source of communication between the epipharynx and the middle ear. The direction of the eustachian tube, beginning from the epipharynx, is upward, backward and outward. It is a bitrumpet canal, with the two narrowest portions facing each other, and is known as the isthmus. The tympanic trumpet has an osseous framework and is therefore constantly open. The pharyngeal trumpet is the gate to the middle ear. It opens and