part of inner ear tympanum BTO:0002098 BrendaTissueOBO The major portion of the middle ear (auris media), consisting of a narrow air-filled cavity in the temporal bone that contains the auditory ossicles. It communicates with the mastoid air cells and the mastoid antrum via the aditus and with the nasopharynx via the auditory tube. The middle ear and the tympanic cavity were formerly regarded as being synonymous. cavitas tympani cavitas tympanica tympanic cavity