| Round window | |
|---|---|
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| View of the inner wall of the tympanum. (label is 'fen. rotund. ' - lower of two black circles. ) | |
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| Interior of right osseous labyrinth. (label is 'cochlear fenestra', at bottom center. ) | |
| Latin | fenestra cochleae, fenestra rotunda |
| Gray's | 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. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. the Peripheral organs of the Special senses the organs of Taste ( Peripheral gustatory or Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group The inner Ear is the bony labyrinth, a system of passages comprising two main functional parts the organ of hearing or Cochlea The middle ear is the portion of the ear internal to the Eardrum, and external to the Oval window of the Cochlea. (The oval window is the other. The oval window (or vestibular window) is a membrane-covered opening which leads from the Middle ear to the vestibule of the inner Ear. 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. Scala vestibuli is a Perilymph filled cavity inside the Cochlea of the Inner ear. The helicotrema (from Greek ἕλιξ meaning coil and τρη̂μα meaning hole is the part of the Cochlear labyrinth where the Scala Scala tympani is one of the Perilymph -filled cavities in the Cochlear labyrinth. )
Contents |
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. The oval window (or vestibular window) is a membrane-covered opening which leads from the Middle ear to the vestibule of the inner Ear.
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 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 inner Ear is the bony labyrinth, a system of passages comprising two main functional parts the organ of hearing or Cochlea In Mathematics, a saddle point is a point in the domain of a function of two variables which is a Stationary point but not a Local extremum 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. The tympanic cavity is a small cavity surrounding the bones of the Middle ear. Fiber or fibre is a class of Materials that are continuous filaments or are in discrete elongated pieces similar to lengths of thread.
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
The stapes bone transmits movement to the oval window. The stapes or stirrup is the stirrup-shaped small Bone or ossicle in the Middle ear which attaches the Incus to the Fenestra ovalis As the oval window membrane moves in, 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. 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 Hair cells are the Sensory receptors of both the Auditory system and the Vestibular system in all Vertebrates. If the round window were to be absent or rigidly fixed (as can happen in some congenital abnormalities), the oval window would be pushing incompressible fluid against the unyielding walls of the cochlea. 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 It would therefore not move to any useful degree leading to a hearing loss of about 60dB. The decibel ( dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity (usually power or intensity relative to This is, unsurprisingly, the same as for conditions where the stapes itself is fixed, such as otosclerosis. Otosclerosis is an abnormal growth of bone of the Middle ear which can result in Hearing loss.
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 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 Hair cells are the Sensory receptors of both the Auditory system and the Vestibular system in all Vertebrates. The round window is often used as an approach for cochlear implant surgery. A 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 It has also recently been used as a site to place middle ear implantable hearing aid transducers. The middle ear is the portion of the ear internal to the Eardrum, and external to the Oval window of the Cochlea. This work has been publicised by Prof. Vittorio Colletti in Verona. Verona is a city and provincial capital in Veneto, Northern Italy. [1]
Additional images
 Cochlea |
References
- ^ 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:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 17062502.
External links
- Diagram (as 'round window') at Southwest Tennessee Community College
- Overview at University of Denver
This article was originally based on an entry from a public domain edition of Gray's Anatomy. Southwest Tennessee Community College is a Community college operated by the Tennessee Board of Regents in Memphis Tennessee, USA. The University of Denver ( DU) founded in 1864 is the oldest private University in the Rocky Mountain Region of the United States. The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone Henry Gray's Anatomy of the Human Body (or Gray's Anatomy as it has commonly been shortened is an English-language Human anatomy Textbook 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.
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