Cochlea is concerned with the sensation of hearing. It is a coiled structure that looks like a snail’s shell. It is a fluid filled structure present in the inner ear (of the membranous labyrinth) and it contains the sound detecting “organ of corti (spiral organ).”
Organ of corti is the auditory receptor that lies on the basilar membrane, and extends throughout cochlear duct.
The motion of fluid in the cochlea causes displacement of basilar membrane and tectorial membrane.
Thus, the blanks can be filled with basilar membrane; tectorial membrane.