Stapedius, along with tensor tympani, is a muscle of the middle ear. It arises from the pyramidal eminence on the posterior wall of the middle ear. It inserts into the neck of the stapes bone.
It acts to pull the stapes posteriorly, so tilting its footplate in relation to the fenestra vestibuli. This has the effect of damping the ossicular chain and hence limits the potential damage caused by loud noise.
Stapedius is innervated by the facial nerve (VII) as it traverses the middle ear.