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:	stapedial branch of posterior auricular artery
Nerve:	facial nerve (tympanic branch)
Action:	control the amplitude of sound waves to the inner ear
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 the tympanic branch of cranial nerve VII, the Facial Nerve.

1 Function
2 Pathology
3 See also
4 External links

[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 primarily dampens 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] See also

Acoustic reflex

[edit] External links

409665614 at GPnotebook
LUC stap
Stapedius+muscle at eMedicine Dictionary

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v • d • e Sensory system: Auditory and Vestibular systems

Outer ear	Pinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) • Ear canal

Middle ear	Eardrum (Umbo) • Ossicles (Malleus, Incus & Stapes) • muscles (Stapedius, Tensor tympani) • Eustachian tube (Torus tubarius)

Inner ear/Labyrinth	Bony labyrinth (Vestibule) • Membranous labyrinth Oval window → Scala vestibuli / Reissner's/vestibular membrane, Helicotrema and Scala tympani / Basilar membrane (Perilymph) → Round window Cochlea: Modiolus • Cochlear duct / scala media (Endolymph, Stria vascularis, Spiral ligament, Organ of Corti), Olivocochlear system Organ of Corti: Stereocilia • Sulcus spiralis (externus, internus) • Limbus spiralis

to brain (auditory)	Tectorial membrane → Hair cells → Spiral ganglion → Cochlear nerve ^VIII → Cochlear nuclei → Trapezoid body → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Auditory radiations → Primary auditory cortex

Vestibular system	Static/translations: Utricle (Macula) – Saccule (Macula, Endolymphatic sac, Endolymphatic duct) – Kinocilium – Otolith Kinetic/rotations: Semicircular canals (Superior, Posterior, Horizontal) • Cupula • Ampullae (Crista ampullaris)

to brain (vestibular)	Vestibular nerve ^VIII → Vestibular nuclei, Flocculonodular lobe Vestibular nuclei → Vestibulospinal tract, Ventral posterolateral nucleus → Vestibular cortex

v • d • e

List of muscles of head and neck: the head

Extraocular (CN III, IV, VI)

oblique (inferior, superior) - rectus (superior, inferior, medial, lateral) - levator palpebrae superioris (superior tarsal)

Mastication (CN V3)

masseter - temporalis - pterygoid (lateral, medial)

Facial (CN VII)

Mouth/throat (CN IX, X, XI)
(except TVP=V3)

Soft palate	veli palatini (tensor, levator) - musculus uvulae - palatopharyngeus (to pharnyx) - palatoglossus (to tongue)

Pharynx	pharyngeal constrictor (superior, middle, inferior) - longitudinal (stylopharyngeus, salpingopharyngeus)

Larynx	cricothyroid - cricoarytenoid (posterior, lateral) - arytenoid (oblique arytenoid/aryepiglottic, transverse arytenoid) - thyroarytenoid (vocal, thyroepiglottic)