Organ of Corti

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Organ of Corti

A cross section of the cochlea illustrating the organ of Corti.

Section through the spiral organ of Corti. Magnified.
Latin	organum spirale
Gray's	subject #232 1056
MeSH	Organ+of+Corti

The organ of Corti (or spiral organ) is the organ in the inner ear of mammals that contains auditory sensory cells, or "hair cells."

[edit] Structure and function

See also: Stereocilia (inner ear)

The organ of Corti has highly specialized structures that respond to fluid-borne vibrations in the cochlea with a shearing vector in the hairs of some cochlear hair cells. It contains between 15,000-20,000 auditory nerve receptors. Each receptor has its own hair cell. The shear on the hairs opens ion channels, leading to neural, electrical signaling to the auditory cortex. The pinna and middle ear act as mechanical transformers, so that by the time sound waves reach the Organ of Corti, their pressure amplitude is 20 times that of the air impinging on the pinna. The Organ of Corti can be damaged by excessive sound levels, leading to noise induced health effects.

[edit] The discoverer: Alfonso Corti

The organ was named after the Italian anatomist Marquis Alfonso Giacomo Gaspare Corti (1822-1876), who conducted microscopic research of the mammalian auditory system.

[edit] Hearing loss

Main article: Hearing impairment

The most common kind of hearing impairment, sensorineural hearing loss, includes as one major cause the reduction of function in the organ of Corti. Specifically, the active amplification function of the outer hair cells is very sensitive to damage from exposure to trauma from overly-loud sounds or to certain "ototoxic" drugs. Once outer hair cells are damaged, they do not regenerate, and the result is a loss of sensitivity and an abnormally large growth of loudness (known as recruitment) in the part of the spectrum that the damaged cells serve.^[1]

[edit] Additional images

Transverse section of the cochlear duct of a fetal cat.	Diagrammatic longitudinal section of the cochlea.	Floor of ductus cochlearis.	Limbus laminæ spiralis and membrana basilaris.
Section through the spiral organ of Corti. Magnified.