Hair Cells

Hair cells get their name from the long stereocilia that extend from their surface toward the tectorial membrane. Recall that immobile stereocilia are actually more closely related to microvilli than they are to cilia, which is motile. When vibrations cause the movement of perilymph and endolymph in the cochlea, the hair cells move relative to the tectorial membrane and either depolarize or hyperpolarize (depending upon the direction of their movement). This change in electric potential is transmitted to the sensory nerves that synapse with the hair cells.