Which structure does the round window interface with?

The round window is a membrane-covered opening located in the cochlea of the inner ear. It plays a crucial role in the hearing process by providing a compliant surface that accommodates the fluid movement within the cochlea, particularly with the pressure waves generated by sound. Specifically, the round window interfaces with the scala tympani, which is one of the three fluid-filled chambers of the cochlea.

When sound waves enter the cochlea through the oval window, they create pressure waves in the perilymph fluid of both the scala vestibuli and scala tympani. The movement of fluid in the scala tympani causes the round window to bulge outward, allowing the fluid to move freely and preventing pressure buildup within the cochlea. This action is essential for the proper functioning of the auditory system, as it ensures that the pressure waves can travel effectively through the cochlea, stimulating the hair cells responsible for converting sound vibrations into neural signals.

The other structures mentioned—scala vestibuli, scala media, and helicotrema—do not have a direct interface with the round window. The scala vestibuli is connected to the oval window, which deals with incoming sound vibrations, while the scala media contains the organ of Corti, where sound transduction occurs.