Which membrane separates the scala media from the scala vestibuli?

The membrane that separates the scala media from the scala vestibuli is Reissner's membrane. This structure plays a crucial role within the cochlea of the inner ear, forming one of the boundaries of the central compartment known as the scala media (or cochlear duct). Reissner's membrane is important because it helps maintain the ionic compositions and pressure differences that are essential for the transduction of sound waves into neural signals, which the brain interprets as sound.

Understanding the function of Reissner's membrane also highlights its significance in the overall operation of the auditory system. It allows for the proper functioning of the cochlear fluid dynamics, which are critical for the conversion of sound vibrations into the auditory signals processed by the hair cells located in the scala media. Other membranes listed, such as the basilar membrane and the tectorial membrane, have different roles; for instance, the basilar membrane supports the organ of Corti and is involved in the mechanical signaling of sound, while the tectorial membrane interacts with hair cells but does not function to separate the compartments within the cochlea. The round window membrane serves to dampen excess pressure in the cochlea and does not separate the scala media from the scala vestibuli.