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 (tympanic branch)
Action	control the amplitude of sound waves to the inner ear

The stapedius is the smallest striated 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 is innervated by the nerve to stapedius, a branch of cranial nerve VII, the Facial Nerve.

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. (Compare the role of the tensor tympani muscle, which primarily dampens those sounds associated with chewing.)

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.

See also

• Acoustic reflex

External links

• 409665614 at GPnotebook
• LUC stap
• Stapedius+muscle at eMedicine Dictionary

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