The
middle ear is the portion of the
ear internal to the
eardrum, and external to the
oval window of the
inner ear. Also mammalian middle ear contains three
ossicles, which transfers the vibrations of the eardrum into waves in the fluid and membranes of the
inner ear. The hollow space of the middle ear has also been called the
tympanic cavity, or
cavum tympani. The
eustachian tube (also known as the auditory tube or the pharyngotympanic tube) joins the tympanic cavity with the nasal cavity (
nasopharynx), allowing pressure to equalize between the middle ear and throat.