Each inner hair fiber has 16-20 associated auditory nerve fibers. 90-95% of the nerve fibers are edicated to the IHC.

Auditory nerve fibers of inner hair cells

Inner hair cells, IHCs, are closer to the central axis of the cochlea. There are about 3500 in a single row.

Grinnell College

There are two sets of hair cells within the organ of Corti. Inner hair cells and outer hair cells. There are also different types of hair cells, such as stereocilia

hair cells (auditory receptors) within the ear

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Inner Hair Cells 

There are three rows of outer hair cells (OHCs) numbering about 12000 hairs. The upper end of each hair has tiny protruding hairs that are relatively stiff. These are called stereocilia.

OHCs put pressure on the tectorial membrane to respond to commands from the brain. The OHCs are able to fine-tune the cochlea for frequency discrimination. When hyperpolarized, the OHC increases in length up to 5% due to the protein prestin. Depolarization causes the OHCs to shorted. Modulating the stiffness of the basilar membrane can lead to better tuning and more pronounced amplification.  They are able to change their lengthand can send messages to IHCs. 

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