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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.

Structure

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.^[1] ^:863

Innervation

The stapedius is innervated by the nerve to stapedius, a branch of the facial nerve.^[1] ^:863

Function

The stapedius dampens the vibrations of the stapes by pulling on the neck of that bone.^[1] ^:863 It prevents excess movement of 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.

Clinical relevance

Paralysis of the stapedius, such as in injury to the facial nerve (CN VII) distal to the geniculate ganglion prior to its branch to stapedius muscle (which would also cause Bell's Palsy), 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.

Evolutionary variation

Like the stapes bone to which it attaches, the stapedius muscle shares evolutionary history with other vertebrate structures.

The mammalian stapedius evolved from a muscle called the depressor mandibulae in other tetrapods, the function of which was to open the jaws (this function was taken over by the digastric muscle in mammals). The depressor mandibulae arose from the levator operculi in bony fish, and is equivalent to the epihyoidean in sharks. Like the stapedius, all of these muscles derive from the hyoid arch and are innervated by cranial nerve VII.^[2]

References

^ ^a ^b ^c Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell ; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN 978-0-8089-2306-0. Cite uses deprecated parameters (help)
^ Kardong, Kenneth V. (1995). Vertebrates: comparative anatomy, function, evolution. McGraw-Hill. pp. 55, 57. ISBN 0-697-21991-7.

External links

409665614 at GPnotebook
Origin, insertion and nerve supply of the muscle at Loyola University Chicago Stritch School of Medicine
Stapedius+muscle at eMedicine Dictionary

UpToDate Contents

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English Journal

Tenotomy of the middle ear muscles causes a dramatic reduction in vertigo attacks and improves audiological function in definite Meniere's disease.

Loader B, Beicht D, Hamzavi JS, Franz P.SourceDepartment of Otorhinolaryngology Head and Neck Surgery, Medical University of Vienna, Vienna General Hospital , Vienna , Austria.
Acta oto-laryngologica.Acta Otolaryngol.2012 May;132(5):491-7. Epub 2011 Dec 27.
Abstract Conclusions: Because the presented data reveal an immediate and persistent reduction of vertigo and a clear improvement in hearing function and functional scales, we conclude tenotomy to be effective in unilateral, definite Meniere's disease - laying the foundation for future prospective
PMID 22201453

Intra- and postoperative electrically evoked stapedius reflex thresholds in children with cochlear implants.

Baysal E, Karatas E, Deniz M, Baglam T, Durucu C, Karatas ZA, Mumbuc S, Kanlikama M.SourceGaziantep University, Medical Faculty, Otolaryngology Department, Turkey.
International journal of pediatric otorhinolaryngology.Int J Pediatr Otorhinolaryngol.2012 May;76(5):649-52. Epub 2012 Feb 18.
OBJECTIVES: The aim of this study was to investigate whether there is a significant correlation between intra- and postoperative electrically evoked stapedius reflex thresholds (eSRTs) in children with cochlear implants.METHODS: Sixty-five pediatric cochlear implant users were included in this study
PMID 22342227

「アブミ骨筋」

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	p.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
	Anatomical terms of muscle

　　[★]

英: stapedius (K), stapedius muscle
ラ: musculus stapedius
関: 顔面神経、耳小骨、アブミ骨筋反射、鼓膜張筋

起始

鼓室後壁の錐体隆起

停止

アブミ骨骨頭

神経

顔面神経

機能

伝音効率をさげる。

発生

第二鰓弓

臨床関連

アブミ骨筋麻痺 (M.537)

聴覚過敏

アブミ骨筋反射検査

「stapedius」

　　[★]

アブミ骨筋、あぶみ骨筋

関: stapedius muscle

[GRAYS2005-1] Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell ; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN 978-0-8089-2306-0. Cite uses deprecated parameters (help)

[kardong-2] Kardong, Kenneth V. (1995). Vertebrates: comparative anatomy, function, evolution. McGraw-Hill. pp. 55, 57. ISBN 0-697-21991-7.

匿名

検索

案内

案内

musculus stapedius