Stapedius muscle Information & Stapedius muscle Links at HealthHaven.com

Stapedius
	The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral view.
	Malleus Tensor Tympani Incus Stapedius Labyrinth Stapes Auditory Canal Tympanic Membrane; (Ear Drum) Eustachian Tube Tympanic cavity
	Bones and muscles in the tympanic cavity in the middle ear
Latin	musculus stapedius
Gray's	subject #230 1046
Origin	walls of pyramidal eminence
Insertion	neck of stapes
Artery	stapedial branch of posterior auricular artery
Nerve	facial nerve (nerve to stapedius)
Actions	control the amplitude of sound waves to the inner ear

The stapedius is the smallest skeletal muscle in the human body. At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the stapes.

The stapedius emerges from a pinpoint foramen 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.

[edit] Function

It prevents excess movement by the stapes, helping to control the amplitude of sound waves from the general external environment to the inner ear. The stapedius muscle dampens the ability of the stapes vibration and protects the inner ear from high noise levels, primarily the volume of your own voice. Compare also the role of the tensor tympani muscle, which primarily dampens those sounds associated with chewing.

[edit] Innervation

The stapedius is innervated by the nerve to stapedius, a branch of cranial nerve VII, the facial nerve. This is the first branch of the facial nerve after it exits the facial canal; the second branch is the chorda tympani, which provides taste sensation to the anterior 2/3 of the tongue.

[edit] Pathology

Paralysis of the stapedius allows wider oscillation of the stapes, resulting in heightened reaction of the auditory ossicles to sound vibration. This condition, known as hyperacusis, causes normal sounds to be perceived as very loud.