Middle ear

The middle ear is an air-filled space, called a cavity, that holds a chain of three bones. These bones include:

• The hammer, also called the malleus.
• The anvil, also called the incus.
• The stirrup, also called the stapes.

The eardrum lies between these bones and the outer ear. Also called the tympanic membrane, the eardrum vibrates when a sound wave strikes it.

A narrow channel called the auditory tube links the middle ear to the back of the nose and upper part of the throat. This channel also is called the eustachian tube.

The tube opens and closes at the throat end to keep the pressure in the middle ear the same as the pressure outside the ear. The pressure needs to be equal on both sides for the eardrum to work as it should. The tube also drains fluids.