middle ear In tetrapods, except for Urodela, Apoda, and snakes (Serpentes), the central chamber of the ear, derived from a gill pouch, lying between the tympanic membrane and the inner ear, linked to the pharynx by the eustachian canal, and containing the ear ossicles. In most mammals it is encased in the bulla.

middle ear (tympanic cavity) The air-filled cavity within the skull of vertebrates that lies between the outer ear and the inner ear. It is linked to the pharynx (and therefore to outside air) via the Eustachian tube and in mammals contains the three ear ossicles, which transmit auditory vibrations from the outer ear (via the tympanum) to the inner ear (via the oval window).

middle ear (tympanic cavity) (mi-d'l) n. the air-filled part of the ear that transmits vibrations from the eardrum to the inner ear via three small bones (see ossicle). It is connected to the pharynx by the Eustachian tube.

mid·dle ear • n. the air-filled central cavity of the ear, behind the eardrum.