The key mechanical elements involved in signal transduction in the cochlea are:
- BASILAR MEMBRANE (BM): resonates when sound is being transduced
- TECTORIAL MEMBRANE (TM): gelatinous material that extends from the spiral limbus (SL) over the apical surface of the hair cells
- the stereocilia of the outer hair cells (OHC) are embedded in the TM, which allows a solid, physical connection between the tectorial and basilar membranes
- the stereocilia of the inner hair cells (IHC) are close enough to the TM that they brush against it when the BM vibrates
- MN = marginal net of the tectorial membrane
- PILLAR CELLS (IP1, OP1): form the tunnel of Corti (also called the inner tunnel) and provide structural support for the reticular lamina that extends across the apical surface of hair cells, pillar and Hensen cells and the Deiter cell processes
- DEITER CELLS: outer hair cells sit in the sockets of the Deiter cells, but are otherwise free from the supporting cells (unlike the inner hair cells that are embedded in the supporting cells of the inner sulcus
- HENSEN CELLS: form the outer rim of the reicular lamina
The reticular lamina forms the boundary between endolymph (salmon colour) and perilymph (blue). Tight junctions prevent mixing of the two fluids. The stereocilia are in endolymph, but the hair cell bodies are in perilymph. Potassium ions flowing through the hair cells during transduction are recycled back to the scala media via the supporting cells and the stria vascularis. |
