Middle

Middle ear

The middle ear is the portion of the ear internal to the eardrum, and external to the inner ear. It includes the auditory ossicles—three small bones (the malleus, incus, and stapes) that transfer sound vibrations from the eardrum to the inner ear. The middle ear is connected to the nasopharynx by the Eustachian tube, which equalizes air pressure in the middle ear.

Anatomy

The middle ear is located in the temporal bone of the skull, and is an air-filled cavity (tympanic cavity). It is separated from the outer ear by the eardrum and from the inner ear by the medial wall of the tympanic cavity. The main components of the middle ear are the tympanic cavity, the auditory ossicles, and the auditory tube.

Tympanic cavity

The tympanic cavity is a small, air-filled space located within the temporal bone. It is lined with a mucous membrane, and is connected to the nasopharynx by the Eustachian tube.

Auditory ossicles

The auditory ossicles are three small bones that form a chain across the middle ear, from the eardrum to the inner ear. They are the malleus (hammer), incus (anvil), and stapes (stirrup). These bones amplify and transfer sound vibrations from the eardrum to the inner ear.

Eustachian tube

The Eustachian tube is a narrow tube that connects the middle ear to the nasopharynx. It functions to equalize air pressure on either side of the eardrum.

Function

The primary function of the middle ear is to transfer sound vibrations from the outer ear to the inner ear. The auditory ossicles amplify these vibrations, allowing for the perception of sound.

Clinical significance

Diseases of the middle ear can lead to hearing loss. These include otitis media, a middle ear infection; otitis media with effusion, a condition in which fluid accumulates in the middle ear; and cholesteatoma, a skin growth that occurs in the middle ear.

See also

• Outer ear
• Inner ear
• Hearing
• Audiology

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