Spiral ganglion

Spiral ganglion is a group of nerve cells located in the cochlea, a part of the inner ear. These cells play a crucial role in the transmission of sound signals from the ear to the brain. The spiral ganglion is named for its spiral shape, which mirrors the coiled structure of the cochlea.

Etymology

The term "spiral ganglion" is derived from the Latin spira, meaning "coil", and ganglion, meaning "knot". This reflects the coiled shape of the ganglion, as well as its function as a nerve knot or junction.

Structure

The spiral ganglion consists of two types of neurons: type I and type II. Type I neurons make up 90-95% of the spiral ganglion and innervate the inner hair cells of the cochlea. Type II neurons, on the other hand, innervate the outer hair cells. The neurons of the spiral ganglion are bipolar, meaning they have two extensions. One extension, the peripheral process, connects to the hair cells of the cochlea, while the other, the central process, connects to the cochlear nucleus in the brainstem.

Function

The primary function of the spiral ganglion is to transmit sound information from the cochlea to the brain. When sound waves enter the ear, they cause the hair cells in the cochlea to move. This movement triggers the release of neurotransmitters, which then stimulate the neurons of the spiral ganglion. The neurons send this information to the brain, which interprets it as sound.

Clinical significance

Damage to the spiral ganglion can result in sensorineural hearing loss, a type of hearing loss caused by problems with the inner ear or the auditory nerve. This can be caused by aging, exposure to loud noise, certain medications, and various diseases. Cochlear implants, a type of hearing aid, can be used to stimulate the spiral ganglion directly, bypassing the damaged hair cells.

See also

• Cochlea
• Neuron
• Sensorineural hearing loss
• Cochlear implant

References

Spiral ganglion Resources
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