The cochlea is a fluid-filled, snail-like structure within a cavity in the inner ear.
This article will describe the structure and function of the cochlea.
Anatomy
The spiral shape of the cochlea is necessary for the transduction of different sound frequencies.
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The cochlea is approximately 10 millimeters (mm) wide.
If it were uncoiled, the cochlea would be approximately 35 mm long.
The cochlear duct is another bony, hollow tube that sits between the scala vestibuli and the scala tympani.
The cochlear duct contains endolymph.
The scala tympani and cochlear duct are separated by the basilar membrane.
Also located within the cochlea are tiny hair cells.
They are specifically found within the organ of Corti and are essential for proper hearing.
At birth, we have about 12,000 hair cells.
Given their essential role in hearing, the loss of hair cells results in permanent sensorineural hearing loss.
Location
The cochlea is one of two main structures that make up the inner ear.
The inner ear is located behind the eardrum and deep within the middle ear.
Behind the eardrum are the ossicles, tiny bones that play a vital role in hearing.
At the bottom of the stapes sits the oval window.
Anatomical Variations
Embryonically, the inner ear begins to form as early on as four weeks gestation.
Sound vibrations continue on through the scala vestibuli and scala tympani, eventually displacing the round window.
Associated Conditions
Several conditions may affect the cochlea.
It includes sensory hearing loss that results from damaged hair cells within the cochlea.
Sensorineural hearing loss is extremely common, especially in the elderly population, but can also be congenital.
It can also be associated withMeniere’s disease.
Sensorineural hearing loss can be divided into central hearing loss or sensory hearing loss.
Tinnitus
Tinnitusis ringing in the ear.
It can also be an underlying buzzing, whistling, or chirping sound.
Pulsatile tinnitus is when you’re free to hear what sounds like your own heartbeat in your ears.
Despite its name, a cochlear implant does not restore normal hearing.
It takes proper training to interpret sound using a cochlear implant.
Tests
The health of the cochlea is assessed by several tests.
TheOAE testspecifically measures the function of the hair cells located in the cochlea.
Summary
The cochlea is a fluid-filled, spiral-shaped cavity found in the inner ear.
It plays an important role in the function of hearing.
Conditions associated with the cochlea include sensorineural hearing loss, acoustic neuroma, and tinnitus.
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