The stapedius emerges from a pinpoint foramen or opening in the apex of the pyramidal eminence (a hollow, cone-shaped prominence in the posterior wall of the tympanic cavity), and inserts into the neck of the stapes.

[2] : 863  As one of the muscles involved in the acoustic reflex it prevents excess movement of the stapes, helping to control the amplitude of sound waves from the general external environment to the inner ear.

[3] Paralysis of the stapedius allows wider oscillation of the stapes, resulting in heightened reaction of the auditory ossicles to sound vibration.

In cases of Bell's palsy, a unilateral paralysis of the facial nerve, the stapedius is paralyzed and hyperacusis may result.

[3] Like the stapes bone to which it attaches, the stapedius muscle shares evolutionary history with other vertebrate structures.