The hammer, anvil and stirrup—also known as the malleus, incus, and stapes, respectively, and collectively, as "middle ear ossicles"—are the smallest bones in the human body.

Now hear this: early mammal fossil shows how sensitive ear bones evolved. Now hear this: ... anvil and hammer bones are still connected to the jaw by another bone—gone from adult modern mammals.

When the ear drum vibrates, it moves these three tiny bones: the hammer, the anvil, and the stirrup. They help carry the sound into the inner ear, which we'll look at now.