Organ of Corti

Structure: < Click on image >

Organ of Corti. (Image modified with permission from a drawing by C. Kaiser). Note the single row of inner hair cells and the three rows of outer hair cells. All hair cells (green) have stereocilia; the inner hair cell stereocilia may only touch the tectorial membrane, while the outer hair cell stereocilia are firmly attached to it. When the cochlea moves, a slight shear force occurs between the basilar and tectorial membranes, which bends the stereocilia, generating electrical signals in the hair cells. These signals are transmitted to distal processes of the spiral ganglion cells which in turn cause action potentials in the cochlear portion of the eighth cranial nerve (vestibulocochlear nerve). The outer hair cells are important in both the sensitivity and tuning of the cochlea. Note however, that the vast majority of the distal processes of the spiral ganglion cells (95 percent) terminate on the inner hair cells.