What do the Malleus Incus and stapes bones do?

These are the three smallest bones in the body and they are situated in the ear.

As sound waves enter the ear they vibrate the eardrum in the same pattern, the vibrations are then conducted along the ossicle chain (malleus and incus) which rocks like a bent lever and forces the footplate of the stapes to act as a piston which pushes and pulls at the flexible window of the cochlea.