The smallest bone in the human body is the stapes bone, also known as the stirrup bone. It is found in the middle ear. The stapes bone is one of the three tiny bones in the middle ear, collectively known as the ossicles. The other two ossicles are the malleus (hammer) and incus (anvil).

The primary function of these ossicles is to transmit sound vibrations from the eardrum to the inner ear. The stapes bone plays a crucial role in this process by transmitting these vibrations to the oval window, which leads to the fluid-filled cochlea in the inner ear, where sound is further processed and converted into nerve signals that are sent to the brain for interpretation. The small size of the stapes bone allows it to efficiently transmit sound while protecting the delicate structures of the inner ear.