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The cochlea is the part of the
inner ear Inner Ear (established in 2007 in Bodø, Norway) is a Norwegian record label initiated and led by the brothers and jazz musicians Tore Johansen and Roger Johansen (musician), Roger Johansen. They opened Inner Ear to release their music when their ...

inner ear
involved in
hearing Schematic diagram of the human ear Hearing, or auditory perception, is the ability to perceive Sound, sounds through an organ, such as an ear, by detecting Vibration, vibrations as periodic changes in the pressure of a surrounding medium. Th ...

hearing
. It is a spiral-shaped cavity in the
bony labyrinth The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts: the vestibule of the ear, vestibule, semicircular canals, and cochlea. These are cavities ho ...

bony labyrinth
, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the
Organ of Corti The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.7 ...

Organ of Corti
, the sensory organ of hearing, which is distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea. The name cochlea derives .


Structure

The cochlea (plural is cochleae) is a spiraled, hollow, conical chamber of bone, in which waves propagate from the base (near the middle ear and the
oval window The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a membrane-covered opening from the middle ear to the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, ...
) to the apex (the top or center of the spiral). The spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2¾ turns about the modiolus. The cochlear structures include: * Three ''scalae'' or chambers: ** the
vestibular duct The vestibular duct or scala vestibuli is a perilymph-filled cavity inside the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, ...
or ''scala vestibuli'' (containing
perilymph Perilymph is an extracellular fluid located within the inner ear. It is found within the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable to that of Blood plasma, plasma and cerebrospinal fluid. Th ...
), which lies superior to the cochlear duct and abuts the oval window ** the
tympanic duct The tympanic duct or scala tympani is one of the perilymph Perilymph is an extracellular fluid located within the inner ear. It is found within the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable ...
or ''scala tympani'' (containing perilymph), which lies inferior to the cochlear duct and terminates at the
round window The round window is one of the two openings from the middle ear The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the inner ear. The mammalian middle ear contains three ossicles, which transfer ...
** the
cochlear duct The cochlear duct (or scala media) is an endolymph Endolymph is the fluid contained in the membranous labyrinth of the inner ear. The major cation in endolymph is potassium, with the values of sodium and potassium concentration in the endolymph be ...
or ''scala media'' (containing
endolymph Endolymph is the fluid contained in the membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers which contain the receptors for the senses of equilibrium and hearing. It is lodged within the bony labyrinth T ...
) a region of high potassium ion concentration that the stereocilia of the hair cells project into * The
helicotrema
helicotrema
, the location where the tympanic duct and the vestibular duct merge, at the apex of the cochlea *
Reissner's membrane The vestibular membrane, vestibular wall or Reissner's membrane, is a diaphragm (acoustics), membrane inside the cochlea of the inner ear. It separates the cochlear duct from the vestibular duct. It helps to transmit vibrations from fluid in the ...
, which separates the vestibular duct from the cochlear duct * The '' osseous spiral lamina'', a main structural element that separates the cochlear duct from the tympanic duct * The
basilar membrane The basilar membrane is a stiff structural element within the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus (coch ...
, a main structural element that separates the cochlear duct from the tympanic duct and determines the mechanical wave propagation properties of the cochlear partition * The
Organ of Corti The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.7 ...

Organ of Corti
, the sensory epithelium, a cellular layer on the basilar membrane, in which sensory hair cells are powered by the potential difference between the perilymph and the endolymph *
hair cells Hair cells are the sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system In Biology, biology, the nervous system is a Complex system, highly complex part of an animal that coordinates its Be ...
, sensory cells in the Organ of Corti, topped with hair-like structures called
stereocilia Stereocilia (or stereovilli) are non-motile apical modifications of the cell. They are distinct from cilia The cilium (; the plural is cilia) is an organelle found on eukaryotic cells in the shape of a slender protuberance that projects from the ...
* The
spiral ligament The periosteum The periosteum is a membrane that covers the outer surface of all bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. Bones protect the various organs of the b ...
. The cochlea is a portion of the inner ear that looks like a snail shell (''cochlea'' is Greek for snail). The cochlea receives sound in the form of vibrations, which cause the stereocilia to move. The stereocilia then convert these vibrations into nerve impulses which are taken up to the brain to be interpreted. Two of the three fluid sections are canals and the third is the 'Organ of Corti' which detects pressure impulses that travel along the auditory nerve to the brain. The two canals are called the vestibular canal and the tympanic canal.


Microanatomy

The walls of the hollow cochlea are made of bone, with a thin, delicate lining of
epithelial tissue Epithelium () is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume ...
. This coiled tube is divided through most of its length by an inner membranous partition. Two fluid-filled outer spaces (ducts or ''scalae'') are formed by this dividing membrane. At the top of the snailshell-like coiling tubes, there is a reversal of the direction of the fluid, thus changing the vestibular duct to the tympanic duct. This area is called the helicotrema. This continuation at the helicotrema allows fluid being pushed into the vestibular duct by the oval window to move back out via movement in the tympanic duct and deflection of the round window; since the fluid is nearly incompressible and the bony walls are rigid, it is essential for the conserved fluid volume to exit somewhere. The lengthwise partition that divides most of the cochlea is itself a fluid-filled tube, the third 'duct'. This central column is called the cochlear duct. Its fluid, endolymph, also contains electrolytes and proteins, but is chemically quite different from perilymph. Whereas the perilymph is rich in sodium ions, the endolymph is rich in potassium ions, which produces an
ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...
ic, electrical potential. The hair cells are arranged in four rows in the Organ of Corti along the entire length of the cochlear coil. Three rows consist of outer hair cells (OHCs) and one row consists of inner hair cells (IHCs). The inner hair cells provide the main neural output of the cochlea. The outer hair cells, instead, mainly 'receive' neural input from the brain, which influences their
motility Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with Sessility (motility), sessility, the ...

motility
as part of the cochlea's mechanical "pre-amplifier". The input to the OHC is from the
olivary body In anatomy, the olivary bodies or simply olives (Latin ''oliva'' and ''olivae'', singular and plural, respectively) are a pair of prominent oval structures in the medulla oblongata, the lower portion of the brainstem. They contain the olivary nucle ...
via the medial olivocochlear bundle. The cochlear duct is almost as complex on its own as the ear itself. The cochlear duct is bounded on three sides by the
basilar membrane The basilar membrane is a stiff structural element within the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus (coch ...
, the ''
stria vascularis The upper portion of the spiral ligament (which forms the outer wall of the cochlear duct) contains numerous capillary A capillary is a small blood vessel The blood vessels are the components of the circulatory system that transport blood th ...
'', and Reissner's membrane. The ''stria vascularis'' is a rich bed of capillaries and secretory cells; Reissner's membrane is a thin membrane that separates endolymph from perilymph; and the basilar membrane is a mechanically somewhat stiff membrane, supporting the receptor organ for hearing, the Organ of Corti, and determines the mechanical wave propagation properties of the cochlear system.


Function

The cochlea is filled with a watery liquid, the
endolymph Endolymph is the fluid contained in the membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers which contain the receptors for the senses of equilibrium and hearing. It is lodged within the bony labyrinth T ...
, which moves in response to the vibrations coming from the middle ear via the oval window. As the fluid moves, the cochlear partition (basilar membrane and organ of Corti) moves; thousands of
hair cell Hair cells are the sensory receptor Sensory neurons, also known as afferent neurons, are neuron A neuron or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cel ...
s sense the motion via their
stereocilia Stereocilia (or stereovilli) are non-motile apical modifications of the cell. They are distinct from cilia The cilium (; the plural is cilia) is an organelle found on eukaryotic cells in the shape of a slender protuberance that projects from the ...
, and convert that motion to electrical signals that are communicated via neurotransmitters to many thousands of nerve cells. These primary auditory neurons transform the signals into electrochemical impulses known as
action potential In physiology Physiology (; ) is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence ...

action potential
s, which travel along the auditory nerve to structures in the brainstem for further processing.


Hearing

The ''
stapes The ''stapes'' or stirrup is a bone in the middle ear of humans and other animals which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its Annular ligament of stapes, annular ligam ...
'' (stirrup) ossicle bone of the middle ear transmits vibrations to the ''
fenestra ovalis The oval window (or fenestra vestibuli) is a membrane-covered opening from the middle ear to the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns ...
'' (oval window) on the outside of the cochlea, which vibrates the perilymph in the ''vestibular duct'' (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air. A pressure increase is achieved by reducing the area ratio from the tympanic membrane (drum) to the oval window (''stapes'' bone) by 20. As pressure = force/area, results in a pressure gain of about 20 times from the original sound wave pressure in air. This gain is a form of
impedance matching In electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons The electron is a subatomic particle In physical sciences, subatomic particles ...
– to match the soundwave travelling through air to that travelling in the fluid–membrane system. At the base of the cochlea, each 'duct' ends in a membranous portal that faces the middle ear cavity: The
vestibular duct The vestibular duct or scala vestibuli is a perilymph-filled cavity inside the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, ...
ends at the
oval window The oval window (or ''fenestra vestibuli'' or ''fenestra ovalis'') is a membrane-covered opening from the middle ear to the cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, ...
, where the footplate of the ''stapes'' sits. The footplate vibrates when the pressure is transmitted via the ossicular chain. The wave in the perilymph moves away from the footplate and towards the
helicotrema
helicotrema
. Since those fluid waves move the cochlear partition that separates the ducts up and down, the waves have a corresponding symmetric part in perilymph of the tympanic duct, which ends at the round window, bulging out when the oval window bulges in. The perilymph in the vestibular duct and the
endolymph Endolymph is the fluid contained in the membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers which contain the receptors for the senses of equilibrium and hearing. It is lodged within the bony labyrinth T ...
in the cochlear duct act mechanically as a single duct, being kept apart only by the very thin
Reissner's membrane The vestibular membrane, vestibular wall or Reissner's membrane, is a diaphragm (acoustics), membrane inside the cochlea of the inner ear. It separates the cochlear duct from the vestibular duct. It helps to transmit vibrations from fluid in the ...
. The vibrations of the endolymph in the cochlear duct displace the basilar membrane in a pattern that peaks a distance from the oval window depending upon the soundwave frequency. The
Organ of Corti The organ of Corti, or spiral organ, is the receptor organ for hearing and is located in the mammalian cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.7 ...

Organ of Corti
vibrates due to outer hair cells further amplifying these vibrations. Inner hair cells are then displaced by the vibrations in the fluid, and depolarise by an influx of K+ via their tip-link-connected channels, and send their signals via neurotransmitter to the primary auditory neurons of the
spiral ganglion The spiral (cochlear) ganglion is a group of neuron cell bodies in the modiolus, the conical central axis of the cochlea The cochlea is the part of the inner ear Inner Ear (established in 2007 in Bodø, Norway) is a Norwegian record label in ...
. The hair cells in the Organ of Corti are tuned to certain sound frequencies by way of their location in the cochlea, due to the degree of stiffness in the basilar membrane. This stiffness is due to, among other things, the thickness and width of the basilar membrane, which along the length of the cochlea is stiffest nearest its beginning at the oval window, where the stapes introduces the vibrations coming from the eardrum. Since its stiffness is high there, it allows only high-frequency vibrations to move the basilar membrane, and thus the hair cells. The farther a wave travels towards the cochlea's apex (the ''helicotrema''), the less stiff the basilar membrane is; thus lower frequencies travel down the tube, and the less-stiff membrane is moved most easily by them where the reduced stiffness allows: that is, as the basilar membrane gets less and less stiff, waves slow down and it responds better to lower frequencies. In addition, in mammals, the cochlea is coiled, which has been shown to enhance low-frequency vibrations as they travel through the fluid-filled coil. This spatial arrangement of sound reception is referred to as
tonotopy In physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology Biology is the natural science that studies life and living organisms, including their anatomy, physic ...
. For very low frequencies (below 20 Hz), the waves propagate along the complete route of the cochlea – differentially up vestibular duct and tympanic duct all the way to the ''helicotrema''. Frequencies this low still activate the Organ of Corti to some extent but are too low to elicit the perception of a
pitch Pitch may refer to: Acoustic frequency * Pitch (music), the perceived frequency of sound including "definite pitch" and "indefinite pitch" ** Absolute pitch or "perfect pitch" ** Pitch class, a set of all pitches that are a whole number of octaves ...
. Higher frequencies do not propagate to the ''helicotrema'', due to the stiffness-mediated tonotopy. A very strong movement of the basilar membrane due to very loud noise may cause hair cells to die. This is a common cause of partial hearing loss and is the reason why users of firearms or heavy machinery often wear
earmuff Earmuffs are clothing accessories or PPE designed to cover a person's ears for Ear protection, hearing protection or for warmth. They consist of a plastic, thermoplastic or metal head-band, that fits over the top or back of the Human head, head, ...

earmuff
s or
earplug An earplug is a device that is inserted in the ear canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear The outer ear, external ear, or auris externa is the external part of ...

earplug
s.


Hair cell amplification

Not only does the cochlea "receive" sound, a healthy cochlea ''generates'' and amplifies sound when necessary. Where the organism needs a mechanism to hear very faint sounds, the cochlea amplifies by the reverse transduction of the OHCs, converting electrical signals back to mechanical in a positive-feedback configuration. The OHCs have a protein motor called
prestin Prestin is a protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme ca ...

prestin
on their outer membranes; it generates additional movement that couples back to the fluid–membrane wave. This "active amplifier" is essential in the ear's ability to amplify weak sounds. The active amplifier also leads to the phenomenon of soundwave vibrations being emitted from the cochlea back into the ear canal through the middle ear (otoacoustic emissions).


Otoacoustic emissions

Otoacoustic emissionAn otoacoustic emission (OAE) is a sound In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Moti ...
s are due to a wave exiting the cochlea via the oval window, and propagating back through the middle ear to the eardrum, and out the ear canal, where it can be picked up by a microphone. Otoacoustic emissions are important in some types of tests for
hearing impairment Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken la ...
, since they are present when the cochlea is working well, and less so when it is suffering from loss of OHC activity.


Role of gap junctions

Gap-junction proteins, called
connexin Connexins (Cx)TC# 1.A.24, or gap junction proteins Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Co ...

connexin
s, expressed in the cochlea play an important role in auditory functioning. Mutations in gap-junction genes have been found to cause syndromic and nonsyndromic deafness. Certain connexins, including connexin 30 and connexin 26, are prevalent in the two distinct gap-junction systems found in the cochlea. The epithelial-cell gap-junction network couples non-sensory epithelial cells, while the connective-tissue gap-junction network couples connective-tissue cells. Gap-junction channels recycle potassium ions back to the endolymph after
mechanotransduction Mechanotransduction ('' mechano'' + '' transduction'') is any of various mechanisms by which cells convert mechanical stimulus into electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between ele ...
in
hair cells Hair cells are the sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system In Biology, biology, the nervous system is a Complex system, highly complex part of an animal that coordinates its Be ...
. Importantly, gap junction channels are found between cochlear supporting cells, but not auditory
hair cells Hair cells are the sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system In Biology, biology, the nervous system is a Complex system, highly complex part of an animal that coordinates its Be ...
.


Clinical significance


Hearing loss


Bionics

In 2009, engineers at the
Massachusetts Institute of Technology Massachusetts Institute of Technology (MIT) is a private Private or privates may refer to: Music * "In Private "In Private" was the third single in a row to be a charting success for United Kingdom, British singer Dusty Springfield, aft ...
created an
electronic chip An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material that is normally silicon. Transistor cou ...

electronic chip
that can quickly analyze a very large range of
radio frequencies Radio frequency (RF) is the oscillation Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of Mechanical equilibrium, equilibrium) or between two or more different states. The ter ...
while using only a fraction of the power needed for existing technologies; its design specifically mimics a cochlea.


Other animals

The coiled form of cochlea is unique to
mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
s. In birds and in other non-mammalian
vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an indiv ...
s, the compartment containing the sensory cells for hearing is occasionally also called "cochlea," despite not being coiled up. Instead, it forms a blind-ended tube, also called the cochlear duct. This difference apparently
evolved Evolution is change in the heritable Heredity, also called inheritance or biological inheritance, is the passing on of Phenotypic trait, traits from parents to their offspring; either through asexual reproduction or sexual reproduction, ...
in parallel with the differences in frequency range of hearing between mammals and non-mammalian vertebrates. The superior frequency range in mammals is partly due to their unique mechanism of pre-amplification of sound by active cell-body vibrations of outer
hair cells Hair cells are the sensory receptor Sensory neurons, also known as afferent neurons, are neurons in the nervous system In Biology, biology, the nervous system is a Complex system, highly complex part of an animal that coordinates its Be ...
. Frequency resolution is, however, not better in mammals than in most lizards and birds, but the upper frequency limit is – sometimes much – higher. Most bird species do not hear above 4–5 kHz, the currently known maximum being ~ 11 kHz in the barn owl. Some marine mammals hear up to 200 kHz. A long coiled compartment, rather than a short and straight one, provides more space for additional octaves of hearing range, and has made possible some of the highly derived behaviors involving mammalian hearing. As the study of the cochlea should fundamentally be focused at the level of hair cells, it is important to note the anatomical and physiological differences between the hair cells of various species. In birds, for instance, instead of outer and inner hair cells, there are tall and short hair cells. There are several similarities of note in regard to this comparative data. For one, the tall hair cell is very similar in function to that of the inner hair cell, and the short hair cell, lacking afferent auditory-nerve fiber innervation, resembles the outer hair cell. One unavoidable difference, however, is that while all hair cells are attached to a
tectorial membrane The tectorial membrane (TM) is one of two acellular membranes in the cochlea of the inner ear, the other being the basilar membrane (BM). "Tectorial" in anatomy means forming a cover. The TM is located above the spiral limbus and the spiral organ ...
in birds, only the outer hair cells are attached to the tectorial membrane in mammals.


History

The name cochlea is derived from the Latin word for ''snail shell'', which in turn is from the
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
κοχλίας ''kokhlias'' ("snail, screw"), from κόχλος ''kokhlos'' ("spiral shell")etymology of "cochleㄷa"
in reference to its coiled shape; the cochlea is coiled in mammals with the exception of
monotreme Monotremes are prototherian mammals of the order Monotremata. They are one of the three main groups of living mammals, along with placentals (Eutheria) and marsupials (Metatheria). Monotremes are typified by structural differences in their brai ...
s.


Additional images

File:Gray920.png, Right osseous labyrinth. Lateral view. File:Gray921.png, Interior of right osseous labyrinth. File:Gray923.png, The cochlea and vestibule, viewed from above. File:Gray928.png, Cross-section of the cochlea.


See also

*
Bony labyrinth The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts: the vestibule of the ear, vestibule, semicircular canals, and cochlea. These are cavities ho ...

Bony labyrinth
*
Membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers which contain the receptors for the senses of equilibrium and hearing. It is lodged within the bony labyrinth The bony labyrinth (also osseous labyrinth or otic capsule) is ...
*
Cochlear implant A cochlear implant (CI) is a surgically implanted neuroprosthesis that provides a person who has bilateral moderate-to-profound sensorineural hearing loss Sensorineural hearing loss (SNHL) is a type of hearing loss Hearing loss is a partial ...

Cochlear implant
*
Cochlear nerve The cochlear nerve (also auditory nerve or acoustic nerve) is one of two parts of the vestibulocochlear nerve The vestibulocochlear nerve (auditory vestibular nerve), known as the eighth cranial nerve, transmits sound and equilibrium (balance) ...
*
Cochlear nuclei The cochlear nuclear (CN) complex comprises two Cranial nerve nucleus, cranial nerve nuclei in the human brainstem, the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN). The ventral cochlear nucleus is unlayered whereas the do ...
* Evolution of the cochlea *
Noise health effects Noise health effects are the physical and psychological health Health, according to the World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are ...


References


Further reading

* * * *


External links

*
"Promenade 'Round the Cochlea"
by R. Pujol, S. Blatrix, T. Pujol et al. at
University of Montpellier The University of Montpellier (french: Université de Montpellier) is a public In public relations Public relations (PR) is the practice of managing and disseminating information from an individual or an organization An org ...

"Histology Videos of The Ear"
{{Authority control Auditory system