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Ear Anatomy

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​There are three anatomical regions of the ear - the outer ear, middle ear and inner ear. Each region of the ear contains structures that play a vital role in your hearing and balance.

Below is a description of these structures, and some examples of conditions that can affect your hearing.

Outer ear

Ear Canal

The ear canal is a cylindrical structure lined by skin. It extends from the outer opening (meatus) to the eardrum.

The ear canal is lubricated by glands in the skin that secrete wax. The wax may plug the canal, causing a loss of hearing.

An infection of the ear canal skin can cause inflammation and painful swelling. Antibiotics are generally used to treat these infections.

Middle ear


The eardrum is a thin membrane that separates the outer ear (ear canal) from the middle ear. Sound waves vibrate the eardrum.

A perforation (hole) in the eardrum may occur as a result of infection, trauma (e.g. swab puncture, waterskiing injury, etc.), or other problems. Eardrum perforations​ may close on their own, but sometimes surgery is required to repair the eardrum.

Ossicles (bones of hearing)

There are three ossicles - the Malleus, Incus and Stapes. The ossicles conduct the sounds from the eardrum into the inner ear.

Diseases such as cholesteatoma and chronic infection can damage or destroy these tiny bones; head trauma may also disrupt the bones.

In some cases, hard plaque deposits can result in decreased mobility of the ossicles. Otosclerosis​ ​causes fixation of the stapes bone. These conditions result in what's known as conductive hearing loss.


The mastoid is a honeycomb of air cells located behind the ear. The air cells are lined by a thin mucous membrane.

The mastoid is connected to the part of the ear where the hearing and balance mechanisms are located. The mastoid can be affected by diseases such as infection and cholesteatoma.

Eustachian tube

The eustachian tube is a structure that helps equalize the pressure in the middle ear. Conditions that affect the function of the eustachian tube may cause problems in the middle ear or the mastoid.

Some of these problems include:

  • Fluid
  • Infection
  • Retractions of the eardrum
  • Cholesteatoma

Inner ear


The labyrinth contains the delicate structures of the inner ear balance mechanism. Diseases of the inner ear structure may cause dizziness or balance problems.


The cochlea is the inner ear organ of hearing. The cochlea is lined by thousands of very small nerve endings. When sound waves cause the fluids in the cochlea to move, it activates the nerve endings.

There are many causes of cochlear hearing loss. Some patients benefit from a hearing aid. In some cases, a cochlear implant​ can be placed to help the patient hear better.


There are four nerves in the internal auditory canal:

  • Two vestibular (balance) nerves
  • One cochlear (hearing) nerve
  • One facial nerve

These nerves have a sheath or covering. In some cases, a growth of the sheath occurs. This is called a neuroma.