Corti

The organ of Corti, sometimes simply called Corti, is the sensory epithelium of hearing located on the basilar membrane within the cochlea of the inner ear. It was described by the Italian anatomist Alfonso Corti in the 19th century and is the primary transducer that converts mechanical sound vibrations into neural signals.

Anatomy: The organ of Corti contains one row of inner hair cells and three rows of outer hair cells, supported by pillar cells and other supporting cells. It sits on the basilar membrane inside the cochlea; the tunnel of Corti lies between the inner and outer hair cells, and the reticular lamina forms the apical barrier. The tectorial membrane overlies the hair cells and interacts with their stereocilia during vibration.

Function: Sound-induced vibrations cause movement of the basilar membrane, bending the stereocilia of hair cells. Deflection opens mechanically gated ion channels, generating receptor potentials. Inner hair cells are the primary sensory receptors that transmit signals via the spiral ganglion to the auditory nerve, while outer hair cells enhance sensitivity and frequency selectivity through electromotility, amplifying motion and sharpening tuning.

Physiology and clinical relevance: The organ exhibits tonotopic organization, with different regions responding to different frequencies along the cochlea. Damage to hair cells or supporting structures can cause sensorineural hearing loss. In mammals, hair cells do not generally regenerate, so therapeutic approaches often rely on amplification or cochlear implants that directly stimulate the auditory nerve.