Stapedius

Infobox Muscle
Name = PAGENAME
Latin = musculus stapedius
GraySubject = 230
GrayPage = 1046

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Caption = The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral view.


MapPos = Stapedius| MapCaption = Bones and muscles in the tympanic cavity in the middle ear | Origin = walls of pyramidal eminence
Insertion = neck of stapes
Blood = stapedial branch of posterior auricular artery
Nerve = facial nerve (tympanic branch)
Action = control the amplitude of sound waves to the inner ear
DorlandsPre = m_22
DorlandsSuf = 12550929
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 tympanic 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

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