Named for the Italian anatomist Alfonso Giacomo Gaspare Corti who discovered it in 1851, the organ of Corti, also called the spiral organ, is a structure found in the inner ear of mammals, which acts as the microphone for our sense of hearing. Like a microphone, the organ of Corti receives the mechanical vibration of sound through the air, and it transduces it into the electrical signals which the nervous system interprets into hearing.
The organ of Corti contains four rows of between 16,000 and 20,000 "hair cells" topped by finger-like filamentous projections called stereocilia, which respond to pressure variations by emitting small pulses of electrical voltage called action potentials. These pulses are transmitted by nearby nerve fibres into the auditory processing center of the brain, where they are interpreted as meaningful sound information. The organ of Corti is primarily responsible for the ability to perceive pitch and loudness of sounds, but not the direction of their origin, which is instead determined inside the brain itself by evaluating the timing in which sound reaches each ear compared to the other.
It is inside the scala media, one of three compartments in the cochlea, and it is situated vertically between the basilar membrane and tectorial membrane.
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