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Information about Round Window

View of the inner wall of the tympanum. (label is 'fen. rotund.' - lower of two black circles.)
Interior of right osseous labyrinth. (label is 'cochlear fenestra', at bottom center.)
Latinfenestra cochleae, fenestra rotunda
subject #232 1051
MeSH Round+Window
Dorlands/Elsevier f_04/12357941
The round window is one of two openings that connect the inner ear to the middle ear. (The oval window is the other. The oval window leads to the scala vestibuli, which leads to the helicotrema, which leads to the scala tympani, which leads to the round window.)

Anatomy

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 can often be much smaller than this.

Function

As the oval window membrane moves in, the round window membrane moves out, 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) then the stapes would be pushing incompressible fluid against the unyielding walls of the cochlea. It would therefore not move to any useful degree. The patient would then get a hearing loss of about 60dB. This is, unsurprisingly, the same as for conditions where the stapes itself is fixed, such as otosclerosis.

Medical implications

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

1. ^ 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

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

 •  • [ e]
Sensory system: Auditory and Vestibular systems
Outer earPinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) • Ear canal
Middle earEardrum • Ossicles (Malleus, Incus & Stapes) • Stapedius • Tensor tympani • Eustachian tube (Torus tubarius)
Inner ear/LabyrinthBony labyrinth (Vestibule) • Membranous labyrinth
Oval window • Helicotrema • Round window
Cochlea: Spiral ganglion • Modiolus • Cochlear duct/scala media (Endolymph, Stria vascularis, Spiral ligament, Organ of Corti) • Scala vestibuli and Scala tympani (Perilymph)
Reissner's/vestibular membrane • Basilar membrane • Tectorial membrane
Organ of Corti: Hair cells • Stereocilia • Sulcus spiralis (externus, internus) • Limbus spiralis
Vestibular systemStatic/translations: Utricle (Macula) - Saccule (Macula, Endolymphatic sac, Endolymphatic duct) - Kinocilium - Otolith
Kinetic/rotations: Semicircular canals (Superior, Posterior, Horizontal) • Cupula • Ampullae (Crista ampullaris)
Brain (auditory)Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex
Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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The inner ear is the bony labyrinth, a system of passages comprising two main functional parts:
  • the organ of hearing, or cochlea
  • and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the vestibule.

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The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear.
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The oval window (or vestibular window) is a membrane-covered opening which leads from the middle ear to the vestibule of the inner ear.

Vibrations arriving at the eardrum are transmitted via the interacting ossicles from the middle ear through the membrane of the
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Scala vestibuli is a perilymph filled cavity inside the cochlea of the inner ear.

It is separated from the scala media by Reissner's membrane and extends from the oval window to the helicotrema where it joins scala tympani.
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The helicotrema is the part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet. It is also known as the cochlear apex.

External links

  • Helicotrema at eMedicine Dictionary

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Scala tympani is the name of one of the perilymph filled cavities in the cochlear labyrinth. It is separated from the scala media by the basilar membrane, and it extends from the round window to the helicotrema, where it continues as scala vestibuli.
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The oval window (or vestibular window) is a membrane-covered opening which leads from the middle ear to the vestibule of the inner ear.

Vibrations arriving at the eardrum are transmitted via the interacting ossicles from the middle ear through the membrane of the
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Macerating refers to softening or breaking into pieces with liquid.

It can refer to a form of food preparation. Raw, dried or preserved fruit or vegetables are soaked in liquid to soften and to absorb the flavor of the liquid.
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The cochlea is the auditory portion of the inner ear. Its core component is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating fluid chambers in the coiled tapered tube of the cochlea.
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The inner ear is the bony labyrinth, a system of passages comprising two main functional parts:
  • the organ of hearing, or cochlea
  • and the vestibular apparatus, the organ of balance that consists of three semicircular canals and the vestibule.

..... Click the link for more information.
In the most general terms, a saddle point for a smooth function (curve, surface or hypersurface) is a point such that the curve/surface/etc. in the neighborhood of this point lies on different sides of the tangent at this point. In certain contexts the definition may vary.
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Mucous may refer to:
  • The adjectival form of mucus, a slippery secretion of the lining of various membranes in the body
  • Mucous membrane, a membrane which secretes mucus

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The tympanic cavity is a small cavity surrounding the bones of the middle ear.

It is formed from the tubotympanic sulcus, an expansion of the first pharyngeal pouch.
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For other meanings of fiber/fibre please see Fiber (disambiguation).


Fiber or fibre[1] is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.
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The cochlea is the auditory portion of the inner ear. Its core component is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating fluid chambers in the coiled tapered tube of the cochlea.
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Location Cochlea
Function Amplify sound waves and transduce auditory information to the Brain Stem

Morphology Unique (see text)
Presynaptic connections None
Postsynaptic connections
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The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the "oval window" which is adjacent to the vestibule of the inner ear. It is the smallest and lightest bone in the human body.
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The cochlea is the auditory portion of the inner ear. Its core component is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating fluid chambers in the coiled tapered tube of the cochlea.
..... Click the link for more information.
The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power) relative to a specified or implied reference level.
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Otosclerosis
Classification & external resources

ICD-10 H 80.
ICD-9 387

Otosclerosis is a progressive degenerative condition of the temporal bone which can result in hearing loss.
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The cochlea is the auditory portion of the inner ear. Its core component is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating fluid chambers in the coiled tapered tube of the cochlea.
..... Click the link for more information.
Location Cochlea
Function Amplify sound waves and transduce auditory information to the Brain Stem

Morphology Unique (see text)
Presynaptic connections None
Postsynaptic connections
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cochlear implant (CI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. The cochlear implant is often referred to as a bionic ear.
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The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear.
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Country Italy
Region Veneto
Province Verona (VR)
Mayor Flavio Tosi

Area km
Population
 - Total (as of April 15, 2006)
 - Density /km
Time zone CET, UTC+1

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digital object identifier (or DOI) is a permanent identifier given to a document, which is not related to its current location. A typical use of a DOI is to give a scientific paper or article a unique identifying number that can be used by anyone to locate details of the paper, and
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Southwest Tennessee Community College is a community college operated by the Tennessee Board of Regents in Memphis, Tennessee, USA. It is the result of a 2001 merger between two institutions started by the Regents in the 1960s, the former
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