The smallest bone in the human body is the stapes, also known as the stirrup bone. It is located in the middle ear and plays a crucial role in transmitting sound vibrations from the outer ear to the inner ear. The stapes is approximately 0.1 inches (2.5 to 3.3 mm) in length and is one of the three tiny bones in the middle ear, collectively called the ossicles, which amplify and conduct sound waves to the cochlea, the fluid-filled part of the inner ear responsible for hearing.