Radial Flow Field of Spiral Cochlea and Its Effect on Stereocilia.

The opening of the ion channels ultimately depends on the movement and energy conversion of the microstructural organization. But the role was not yet clear how the active sound amplification function is generated by the microstructure in the cochlear characteristic spiral shape. In this paper, an analytical model of the spiral cochlea is developed to investigate the radial flow field generated by the spiral shape of the cochlea and its effect on the outer hair cell stereocilia, and to analyze the effect of the spiral shape on the micromechanics of the cochlea. The results show that the spiral shape of the cochlea exerts a radial shear force on the hair cell stereocilia by generating a radial flow field, causing the stereocilia to deflect in the radial flow field, with the maximum deflection occurring at the apex of the cochlea. This finding explains from the microscopic mechanism that cochlear spiral shape can enhance low-frequency hearing in humans, which provides a basis for further studies on the contribution of the movement of stereocilia applied by the radial flow field of lymphatic fluid to activate ion channels for auditory production.