The Smallest Bone in the Human Body Is in the Ear

The human body's tiniest structural component is hidden deep inside the ear. The stapes (or stirrup bone) in the middle ear is the smallest bone in the human body, measuring only about 3mm in length — smaller than a grain of rice. The stapes is also one of three tiny bones in the middle ear collectively called ossicles.

The ossicles (malleus, incus, and stapes — or hammer, anvil, and stirrup) transmit sound vibrations from the eardrum to the inner ear. They amplify sound by a factor of about 22. These three bones are the only bones in the human body that are fully formed at birth and never grow larger throughout a person's entire life.