Stapedius

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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:
Nerve:	facial nerve
Action:
Dorlands/Elsevier	m_22/12550929

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 a branch of Cranial Nerve VII, the facial nerve.

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

[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.

[edit] External links

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

v • d • e Sensory system: Auditory system

Outer ear: Pinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) - Ear canal Middle ear: Eardrum - Ossicles (Malleus, Incus & Stapes) - Stapedius - Tensor tympani - Eustachian tube (Torus tubarius) Inner ear/Labyrinth: Bony labyrinth - Membranous labyrinth - Cochlea (Cochlear duct, Scala vestibuli, Scala media & Scala tympani) - Oval window - Helicotrema - Round window - Basilar membrane - Reissner's membrane - Organ of Corti - Hair cells - Stereocilia - Sulcus spiralis externus - Sulcus spiralis internus - Tectorial membrane - Vestibule Brain: Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex