Geometry and mesh of cross-sections at apical (a) and basal (b) regions of the cochlea. and indicate the radial and transverse directions, respectively. The TM and OC are modelled as 2D elastic domains. The TM is homogeneous, whereas the OC contains different subdomains representing discrete cellular structures. The OC has the RL as its top boundary and rests on the BM, which is represented by an orthotropic clamped plate. The TM-RL gap is the narrow fluid-filled space between the RL and the lower surface of the TM. Stereocilia of the OHCs elastically couple the RL and TM (reprinted from PNAS, 101, Cai et al., Evidence of Tectorial Membrane Radial Motion in a Propagating Mode of a Complex Cochlear Model, 6243–6248, Copyright (2004) National Academy of Sciences, USA).
