The smallest bone in the human body, found in the ear, is the stapes.
The stapes is the third of three tiny middle-ear ossicles, following the malleus and incus. It is commonly called the stirrup because its shape resembles an equestrian stirrup. The bone rests against the oval window, an opening into the inner ear, and transfers vibrations from the incus into the fluid-filled cochlea.
This mechanical chain is essential for hearing. Sound moves the eardrum, the malleus passes the vibration to the incus, and the stapes delivers it to the inner ear. The oval window then converts the movement into waves that stimulate sensory cells involved in hearing.
The stapes is often confused with the incus or malleus because all three are exceptionally small bones. The stapes is not merely the smallest ear structure; it is the smallest and lightest bone in the entire human body. Its name comes from the Latin word for stirrup. A disorder called otosclerosis can immobilize it and cause conductive hearing loss.