cochlea

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cochlea

 [kok´le-ah]
a spiral tube shaped like a snail shell, forming part of the inner ear; it is the essential organ of hearing. adj., adj coch´lear.

The cochlea is filled with fluid and is connected with the middle ear by two membrane-covered openings, the oval window (fenestra vestibuli) and the round window (fenestra cochleae). Inside it is the organ of corti, a structure of highly specialized cells that translate sound vibrations into nerve impulses. The cells of this organ have tiny hairlike strands (cilia) that protrude into the fluid of the cochlea.

Sound vibrations are relayed from the tympanic membrane (eardrum) by the bones of hearing in the middle ear to the oval window, where they set up corresponding vibrations in the fluid of the cochlea. These vibrations move the cilia of the organ of Corti, which then sends nerve impulses to the brain.

coch·le·a

, pl.

co·chle·ae

(kok'lē-ă, lē-ē), [TA]
The snail shell-shaped dense bone in the petrous portion of the temporal bone, forming the anterior division of the labyrinth or internal ear (bony cochlea). It surrounds a spiral canal of two-and-one-half turns around a central core, the modiolus; this spiral canal contains the scala vestibuli, scala media consisting of the membranous cochlea or cochlear duct in which is located the spiral organ (Corti), and scala tympani. The scala vestibuli is separated from the scala media by the Reissner membrane, and the basilar membrane separates the scala media from the scala tympani.
[L. snail shell]

cochlea

/coch·lea/ (kok´le-ah)
1. anything of a spiral form.
2. a spiral tube forming part of the inner ear, which is the essential organ of hearing. coch´lear

cochlea

(kŏk′lē-ə, kō′klē-ə)
n. pl. coch·leae (-lē-ē′, -lē-ī′) also coch·leas
A spiral-shaped cavity of the inner ear that resembles a snail shell and contains nerve endings essential for hearing.

coch′le·ar adj.

cochlea

[kok′lē·ə]
Etymology: L, snail shell
the auditory portion of the inner ear. It is a spiral tunnel about 30 mm long with two full and three quarter-turns, resembling a tiny snail shell and containing the sense organ for hearing. cochlear, adj.
enlarge picture
Cochlea

bony labyrinth

The bone encasement of the inner ear which is filled with perilymph and contains 3 cavities:
(1) The cochlea, which houses the sensory part of the auditory system;
(2) The semicircular canals, which are sensitive to rotational movement;
(3) The vestibule, which contains the sacculus and utriculus, which are sensitive to linear movement.

coch·lea

, pl. cochleae (koklē-ă, -ē) [TA]
A conic cavity in the petrous portion of the temporal bone, forming one of the divisions of the labyrinth or internal ear. It consists of a spiral canal making two-and-a-half turns around a central core of spongy bone, the modiolus; this spiral canal of the cochlea contains the membranous cochlea, or cochlear duct, in which is the spiral organ (Corti organ).
[L. snail shell]
Enlarge picture
STRUCTURES OF THE COCHLEA

cochlea

(kŏk′lē-ă) [Gr. kokhlos, land snail]
A winding cone-shaped tube forming a portion of the bony labyrinth of the inner ear. It contains the organ of Corti, the receptor for hearing.

The cochlea is coiled, resembling a snail shell, winding two and three quarters turns about a central bony axis, the modiolus. Projecting outward from the modiolus, a thin bony plate, the spiral lamina, partially divides the cochlear canal into an upper passageway, the scala vestibuli, and a lower one, the scala tympani. Between the two scalae is the cochlear duct, the auditory portion of the membranous labyrinth. The spiral organ (of Corti) lies on its floor. The base of the cochlea adjoins the vestibule. At the cupola or tip, the two scalae are joined at the helicotrema.

See: illustrationcochlear (-ăr), adjective

cochlea

The structure in the inner ear containing the coiled transducer, the organ of Corti, that converts sound energy into nerve impulse information. The cochlea resembles a snail shell.
Cochleaclick for a larger image
Fig. 110 Cochlea . Cross section.

cochlea

a part of the inner ear which is concerned with the detection of the pitch and volume of sound received by the ear. A projection of the SACCULE (2), it occurs in some reptiles, birds and mammals. In the mammal it is a coiled tube consisting of three parallel canals and contains the organ of Corti, the part which actually responds to sound.

Cochlea

The hearing part of the inner ear. This snail-shaped structure contains fluid and thousands of microscopic hair cells tuned to various frequencies, in addition to the organ of Corti (the receptor for hearing).

coch·lea

, pl. cochleae (koklē-ă, -ē) [TA]
Snail shell-shaped dense bone in the petrous portion of the temporal bone, forming the anterior division of the labyrinth or internal ear.
[L. snail shell]

cochlea

a spiral tube forming part of the inner ear, shaped like a snail shell, which is the essential organ of hearing.
The cochlea is filled with fluid and is connected with the middle ear by two membrane-covered openings, the oval window (fenestra vestibuli) and the round window (fenestra cochleae). Inside the cochlea is the organ of Corti, a structure of highly specialized cells that translate sound vibrations into nerve impulses. The cells of this organ have tiny hairlike strands (cilia) that protrude into the fluid of the cochlea.
Sound vibrations are relayed from the tympanic membrane (eardrum) by the ear ossicles in the middle ear to the oval window of the cochlea, where they set up corresponding vibrations in the fluid of the cochlea. These vibrations move the cilia of the organ of Corti, which then sends nerve impulses to the brain. Called also osseus cochlea. See also hearing.

tibial cochlea
articular surface of the distal extremity of the tibia.
References in periodicals archive ?
Many children and some adults with perceptive deafness, however, have a lesion involving the cochlea and not the higher centers, and could be helped when their deafness is severe.
It is possible that an objective test of hearing using preliminary electrical stimulation of the cochlea could be devised.
If this was possible, it would then have to be decided whether this could be done by stimulating the auditory nerve as a whole, or whether local stimulation of different groups of nerve fibers in the cochlea would be sufficient.
5) If the answers to these questions indicate that stimulation of the auditory nerve fibers near their terminations in the cochlea is important, then it will be necessary to know more about the internal resistances and lines of current flow in the cochlea, and whether the electrical responses normally recorded are a reflection of the transduction of sound into nerve discharges, or directly responsible for stimulating the nerve endings.
The research that I undertook in 1967 on the cat brainstem determined the extent to which neurons could follow the electrical stimulation rate of auditory nerve fibers in the cochlea without being suppressed by inhibitory mechanisms [19-20].
The research demonstrated that cats could only adequately discriminate stimulus rates of 100 and 200 pps for both electrodes at the basal (high-frequency) and apical (low-frequency) ends of the cochlea [23,26].
Thus it was important to know whether electrical current could be adequately localized to separate groups of auditory nerve fibers in the cochlea for place coding mid to high frequencies of speech, because these are specially relevant to understanding consonants.
They also showed that current was best localized with bipolar stimulation of the peripheral auditory nerve fibers in the cochlea, with current flowing in a radial rather than longitudinal direction (Figure 5).
The researchers studied cells taken from a part of the rat cochlea that doesn't normally grow hairs.
Hair cells normally arise from cells in a part of the cochlea called the sensory epithelium.
Whether hair cells generated in this part of the cochlea will reverse deafness "is the great big question," says Ruth Anne Eatock, a sensory physiologist at Baylor College of Medicine in Houston.
With that device, you can get much of the same information that people with a cochlear implant receive, although the signal is not as differentiated because the cochlea has some important functions in terms of passing on high--and low-frequency information.