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middle ear
the second part of the ear, separated from the outer ear by the tympanic membrane (eardrum) . It contains the three ossicles, the malleus (hammer), incus (anvil), and stapes (stirrup), so called because of their resemblance to these objects. These three small bones form a chain across the middle
ear from the eardrum to the oval window. The stapes causes a membrane in the oval window to vibrate, and the vibrations are transmitted to the inner ear. The middle ear is also connected to the nasopharynx by the eustachian tube, through which the air pressure in the middle ear is equalized with the air pressure in the nose and throat. This part of
the ear is also connected with the cells in the mastoid bone behind the outer ear. Two muscles attached to the ossicles contract when loud noises strike the tympanic membrane; this limits its vibration and thus protects the middle and inner ear from damage.
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