Tensor tympani

Infobox Muscle
Name = PAGENAME
Latin = musculus tensor tympani
GraySubject = 231
GrayPage = 1046


Caption = The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above.

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Caption2 = The medial wall and part of the posterior and anterior walls of the right tympanic cavity, lateral view. (Label for "Tensor tympani muscle" is at right, second from bottom.)


MapPos = Tensor tympani | MapCaption = Bones and muscles in the tympanic cavity in the middle ear
Origin = auditory tube
Insertion = handle of the malleus
Blood = superior tympanic artery
Nerve = medial pterygoid nerve from the mandibular nerve (V3)
Action = tensing the tympanic membrane
DorlandsPre = m_22
DorlandsSuf = 12551096
The tensor tympani, the larger of the two muscles of the tympanic cavity, is contained in the bony canal above the osseous portion of the auditory tube, from which it is separated by the septum canalis musculotubarii.

Origin and insertion

It arises from the cartilaginous portion of the auditory tube and the adjoining part of the great wing of the sphenoid, as well as from the osseous canal in which it is contained.

Passing backward through the canal, it ends in a slender tendon which enters the tympanic cavity, makes a sharp bend around the extremity of the septum, and is inserted into the manubrium of the malleus, near its root.

Function

When tensed, the action of the muscle is to pull the malleus medially, tensing the tympanic membrane, damping vibration in the ear ossicles and thereby reducing the amplitude of sounds. This muscle is contracted primarily to dampen the noise produced by chewing. (Compare to the more general dampening function of the stapedius muscle.)

In many people with hyperacusis, an increased activity develops in the tensor tympani muscle in the middle ear as part of the startle response to some sounds. This lowered reflex threshold for tensor tympani contraction is activated by the perception/anticipation of loud sound, and is called tonic tensor tympani syndrome (TTTS). In some people with hyperacusis, the tensor tympani muscle can contract just by thinking about a loud sound. Following exposure to intolerable sounds, this contraction of the tensor tympani muscle tightens the ear drum, which can lead to the symptoms of ear pain/a fluttering sensation/a sensation of fullness in the ear (in the absence of any middle or inner ear pathology) [http://www.tinnitusvic.asn.au/tinnitus-hyperacusis.htm] [http://www.tinnitus.org/home/frame/Tensor%20tympani%20syndrome_Klochoff.pdf] . A small percentage of the population can actually voluntarily contract this muscle, inducing a noticeable and (until explained) odd 'rumbling' sound to occur [http://www.madsci.org/posts/archives/1999-09/937369459.Gb.r.html] .

Innervation

Innervation of the muscle is from branches of the mandibular division of the trigeminal nerve (V), by way of the Trigeminal ganglion.

=Additional

ee also

*Acoustic reflex
*Otoacoustic emission
*Equal-loudness contours
*Audiometry
*Hyperacusis

External links

*
*
* [http://audilab.bmed.mcgill.ca/~daren/3Dear/mid3.html McGill]
* MadSci Network [http://www.madsci.org/posts/archives/1999-09/937369459.Gb.r.html]