What Is the Purpose of the Bones in the Middle Ear?
Hearing is a complex process that involves several parts of the ear, including the outer ear, the middle ear, and the inner ear. In addition to hearing, the inner ear helps with balance. The middle ear sits between the outer ear and the inner ear. These three components of the ear work in concert to both help us hear and help us maintain balance.
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The Bones
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The three bones of the middle ear are the malleus, the incus, and the stapes. They sit above a tube that helps to keep the air pressure equalized between the outside air pressure and the middle ear. This is called the Eustachian tube.
The three bones are connected in a series. The malleus connects the eardrum to the incus. The incus connects the malleus to the stapes. The stapes connects the incus to the cochlea in the inner ear. Sound waves cause the eardrum to vibrate, and these bones transfer the vibrations to the inner ear.
Malleus
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The malleus is a rounded bone that has two legs. One leg attaches to the eardrum. The malleus is often described as looking like a hammer. The movements of this bone transfer farther into the middle ear to the incus.
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Incus
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The incus is the middle bone in the middle ear. It is often described as looking like an anvil. This may be because of the association of a hammer hitting the anvil, as the malleus transfers motion to the incus.
Stapes
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The stapes is often called the stirrup. This stirrup-shaped bone takes motion from the incus and transfers it to the inner ear, where it is converted to nerve signals that can be interpreted by the brain. In some cases, the stapes bone has calcium deposits that affect hearing. The surgical procedure to remove that buildup from the stapes bone is called a stapedectomy.
Damage to the Bones
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Damaged bones of the middle ear can result in impaired hearing. There are three probable ways that these bones can be damaged. One is genetic. Some babies are born with malformed bones of the middle ear that interfere or prevent hearing.
A second way these bones can be damaged is through infection or injuries. A head concussion can sometimes damage them.
In some cases, a sharp object inserted in the ear can penetrate the eardrum and damage the small bones of the middle ear.
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References
- Photo Credit ear image by Connfetti from Fotolia.com
