WordNet

the snail-shaped tube (in the inner ear coiled around the modiolus) where sound vibrations are converted into nerve impulses by the organ of Corti
a small opening covered with membrane (especially one in the bone between the middle and inner ear)

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(耳の)蝸牛穀(かぎゅうかく)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/09 01:06:19」(JST)

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The round window is one of the two openings from the middle ear into the inner ear. It is sealed by the round window membrane, which vibrates with opposite phase to vibrations entering the inner ear through the oval window. It allows fluid in the cochlea to move, which in turn ensures that hair cells of the basilar membrane will be stimulated and that audition will occur.

Structure

The round window is situated below and a little behind the oval window, from which it is separated by a rounded elevation, the promontory.

It is placed at the bottom of a funnel-shaped depression (the round window niche) and, in the macerated bone, opens into the cochlea of the internal ear; in the fresh state it is closed by a membrane, the secondary tympanic membrane or round window membrane, which is a complex saddle point shape. The visible central portion is concave toward the tympanic cavity and convex toward the cochlea but towards the edges, where it is hidden in the round window niche, it curves the other way.

This membrane consists of three layers:

an external, or mucous, derived from the mucous lining of the tympanic cavity;
an internal, from the lining membrane of the cochlea;
and an intermediate, or fibrous layer.

Both the oval and round windows are about the same size, approximately 2.5 mm². The entrance to the round window niche is often much smaller than this.

Function

The stapes bone transmits movement to the oval window. As the stapes footplate moves into the oval window, the round window membrane moves out, and this allows movement of the fluid within the cochlea, leading to movement of the cochlear inner hair cells and thus hearing. If the round window were to be absent or rigidly fixed (as can happen in some congenital abnormalities), the stapes footplate would be pushing incompressible fluid against the unyielding walls of the cochlea. It would therefore not move to any useful degree leading to a hearing loss of about 60dB. This is, unsurprisingly, the same as for conditions where the stapes itself is fixed, such as otosclerosis.

Clinical significance

The round window sometimes fails to develop correctly and causes the hearing loss mentioned above. Unfortunately round window malformations are often associated with other ear malformations and the hearing loss can be much more severe. Some types of ear surgery (now generally abandoned) used to leave the round window open to the outside world and covered over the oval window. Sound pressure therefore hit the round window but was shielded from the oval window. It therefore travelled "backwards" around the cochlea but still gave useful hearing as the hair cells were still deflected in the same way. The round window is often used as an approach for cochlear implant surgery. It has also recently been used as a site to place middle ear implantable hearing aid transducers. This work has been publicised by Prof. Vittorio Colletti in Verona.^[1]

Additional images

Cochlea

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

^ Colletti V, Soli SD, Carner M, Colletti L (2006). "Treatment of mixed hearing losses via implantation of a vibratory transducer on the round window". International journal of audiology 45 (10): 600–8. doi:10.1080/14992020600840903. PMID 17062502.

External links

Diagram (as 'round window') at Southwest Tennessee Community College
Overview at University of Denver

UpToDate Contents

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1. 小児における聴覚障害：病因 hearing impairment in children etiology
2. 成人における難聴の病因 etiology of hearing loss in adults
3. 老人性難聴 presbycusis
4. 遺伝性腎炎（アルポート症候群）の遺伝学、病因、および病理 genetics pathogenesis and pathology of hereditary nephritis alport syndrome
5. 耳の先天異常 congenital anomalies of the ear

English Journal

Cochlear implantation with the nucleus slim straight electrode in subjects with residual low-frequency hearing.

Skarzynski H1, Lorens A, Matusiak M, Porowski M, Skarzynski PH, James CJ.Author information 11Institute for Physiology and Pathology of Hearing, Warsaw, Poland; and 2Cochlear France, Toulouse, France.AbstractOBJECTIVES: To measure benefit in terms of speech recognition in quiet and in noise, and conservation of residual hearing in three groups of subjects implanted with the Nucleus Straight Research Array cochlear implant. This device incorporates the Nucleus Slim Straight electrode carrier designed to be easier to insert into the cochlea via the round window while potentially minimizing insertion trauma.
Ear and hearing.Ear Hear.2014 Mar-Apr;35(2):e33-43. doi: 10.1097/01.aud.0000444781.15858.f1.
OBJECTIVES: To measure benefit in terms of speech recognition in quiet and in noise, and conservation of residual hearing in three groups of subjects implanted with the Nucleus Straight Research Array cochlear implant. This device incorporates the Nucleus Slim Straight electrode carrier designed to
PMID 24556970

Direct round window stimulation with the Med-El Vibrant Soundbridge: 5 years of experience using a technique without interposed fascia.

Skarzynski H1, Olszewski L, Skarzynski PH, Lorens A, Piotrowska A, Porowski M, Mrowka M, Pilka A.Author information 1Institute of Physiology and Pathology of Hearing, ul Mochnackiego 10, 02-042, Warsaw, Poland, skarzynski.henryk@ifps.org.pl.AbstractThe objective of this study was to present 5 years of surgical experience, and the extended results of hearing preservation (based on 3-year follow-up), with the Med-El Vibrant Soundbridge (VSB) in which the floating mass transducer (FMT) is placed directly against the round window membrane, and the fascia is used only as covering tissue to keep it in position. A retrospective survey of surgical and audiological data was conducted to evaluate the performance and stability of patient hearing, with audiometric measurements performed over fixed time intervals up to 36 months. 21 patients, aged 19-62 years (mean 48.4), with mixed or conductive, bilateral or unilateral hearing loss were included in this study. Surgical intervention involved monaural implantation of the Med-El VSB between 2006 and 2009. The results were assessed using pure tone audiometry. In 5 years of experience with the technique, no significant complications or device extrusion were observed except for two revision surgeries requiring FMT repositioning. In the 3-year follow-up, we observed stable hearing in the implanted ear. It is concluded that direct round window stimulation without interposed fascia is an alternative for patients with hearing impairment caused by chronic otitis media and/or lack of ossicles, especially after modified radical mastoidectomy. It allows good results in a selected group of patients, although further observation on a larger population is needed to confirm long-term validity and effectiveness.
European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery.Eur Arch Otorhinolaryngol.2014 Mar;271(3):477-82. doi: 10.1007/s00405-013-2432-1. Epub 2013 Mar 20.
The objective of this study was to present 5 years of surgical experience, and the extended results of hearing preservation (based on 3-year follow-up), with the Med-El Vibrant Soundbridge (VSB) in which the floating mass transducer (FMT) is placed directly against the round window membrane, and th
PMID 23512431

Japanese Journal

人胎児蝸牛小管及蝸牛窓の発生学的研究

日本医科大学雑誌 26(8), 716-736, 1959
NAID 130003917179

血管内移植ニ於ケル惡性腫瘍發生増殖ニ關スル實驗的研究 : 殊ニ鼻腔ニ於ケル轉移肉腫ノ發育増殖ニ就テ

京都府立医科大学雑誌 2A(1/2/3), 891-"922-2", 1928
NAID 110007106304

Related Pictures

★リンクテーブル★

リンク元	「正円窓」
関連記事	「cochleae」

「正円窓」

Round window
	Middle ear, with round window at right.
	Interior of right osseous labyrinth (label is cochlear fenestra, at bottom center)
Details
Latin	Fenestra cochleae, fenestra rotunda
Identifiers
Gray's	p.1051
MeSH	A09.246.631.246.814
Dorlands; /Elsevier	f_04/12357941
TA	A15.3.02.015
FMA	56932
	Anatomical terminology