The basilar membrane ripple is driven by what in the cochlea?

The basilar membrane ripple is driven by what in the cochlea?

• A. Temperature gradients.
• B. Electrical potentials generated by outer hair cells.
• C. Pressure differences in the cochlear fluids.
• D. Blood flow changes.

Answer: (C)

Sound-induced movement of the stapes creates a pressure difference across the basilar membrane by pushing on the fluid in the scala vestibuli while the scala tympani responds on the other side. This pressure difference mechanically drives the basilar membrane to ripple, producing a traveling wave that moves along its length. The membrane’s stiffness varies from base to apex, so each frequency sends the peak motion to a specific location. Outer hair cells can amplify this motion via active feedback, but the initial ripple is generated by the pressure difference in the cochlear fluids, not by temperature changes, blood flow, or direct electrical potentials.

Sound-induced movement of the stapes creates a pressure difference across the basilar membrane by pushing on the fluid in the scala vestibuli while the scala tympani responds on the other side. This pressure difference mechanically drives the basilar membrane to ripple, producing a traveling wave that moves along its length. The membrane’s stiffness varies from base to apex, so each frequency sends the peak motion to a specific location. Outer hair cells can amplify this motion via active feedback, but the initial ripple is generated by the pressure difference in the cochlear fluids, not by temperature changes, blood flow, or direct electrical potentials.