Scala tympani

Scala tympani is the name of one of the perilymph filled cavities in the cochlear labyrinth. It is separated from the scala media by the basilar membrane, and it extends from the round window to the helicotrema, where it continues as scala vestibuli.

The purpose of the perilymph filled scala tympani and scala vestibuli is to transduce the movement of air that causes the tympanic membrane and the ossicles to vibrate, to movement of liquid which, depending of frequency, causes the basilar membrane to reach a peak amplitude at a specific site. This movement is conveyed to the organ of Corti inside the scala media, composed of hair cells attached to the basilar membrane and their sterocilia embedded in the tectorial membrane. The movement of the basilar membrane compared to the static tectorial membrane causes the sterocilia to bend. They then depolarise and send impulses to the brain via the cochlear nerve. This produces the sensation of sound.