An ossicle is one of the three tiny bones in the middle ear that transmit sound vibrations from the eardrum toward the inner ear. Collectively, these bones are called the ossicles.
The three ossicles are the malleus, incus, and stapes. The malleus is attached to the eardrum and receives its vibrations. These vibrations pass to the incus and then to the stapes, whose base moves against the oval window of the inner ear.
The ossicles help transmit sound energy from the air-filled middle ear into the fluid-filled inner ear. Their arrangement also provides a mechanical advantage that helps overcome the difference in acoustic impedance between air and the inner-ear fluids, supporting efficient sound transmission.
Conditions that damage or disrupt the ossicles, including injury, certain infections, or otosclerosis affecting the stapes, can interfere with sound transmission and cause conductive hearing loss.
QUICK FACT
- The stapes is the smallest bone in the human body.
- The ossicles form a connected chain that transmits vibrations from the eardrum toward the inner ear.
- Problems affecting the ossicles can reduce air-conduction hearing, while bone conduction may still stimulate the cochlea if inner-ear function is sufficiently preserved.
COMMONLY CONFUSED WITH
- Eardrum: Vibrates in response to sound and transfers these vibrations to the malleus.
- Cochlea: A fluid-filled structure in the inner ear that converts mechanical vibrations into electrical signals for hearing.
- Bone conduction: Transmits vibrations through the bones of the skull to stimulate the cochlea without relying on the usual air-conduction pathway through the eardrum and ossicles.
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