On the functions of the membrana tympani, the ossicles and muscles of the tympanum, and of the eustachian tube in the human ear, with an account of the muscles of the eustachian tube and their action in different classes of animals

Abstract

The author commences his paper by making some observations on the general arrangements of the ossicula auditûs . The malleus and incus being firmly connected together by ligaments, are considered as a single bone, forming an elastic arch, the anterior extremity of which is firmly attached to the Glasserian fissure, the posterior to the anterior part of the mastoid cells. This arch is kept steady by the actions of the tensor tympani. The movement of this arch is that of rotation; and it is effected by the tensor tympani muscle. When this muscle contracts, the lower part of the arch, consisting of the handle of the malleus and the long process of the incus, is drawn inwards; by this action the membrana tympani is rendered tense, and the stapes being pressed towards the cavity of the labyrinth, the fluid in the latter is compressed.