Britannica Sources used in this answer

What are the scala vestibuli and scala tympani in the cochlea?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Cross-section diagram of the human ear showing the outer ear, middle ear, and inner ear, with labeled parts including the auricle, auditory canal, tympanic membrane, ossicles, cochlea, semicircular canals, and nerves. — human ear Structure of the human ear.

In the anatomy of the human ear, the cochlea is a spiral structure divided into compartments by the osseous spiral lamina and the cochlear duct. The scala vestibuli (vestibular ramp) and the scala tympani (tympanic ramp) are the two primary chambers of the cochlea.1

Key details regarding these structures include:

Function and Composition: Both the scala vestibuli and the scala tympani are filled with a fluid called perilymph.12
Location: The scala vestibuli is the upper chamber, while the scala tympani is the lower chamber. They are separated by the cochlear duct (scala media), which contains endolymph.12
Communication: The two scalae communicate with each other through an opening at the apex of the cochlea known as the helicotrema.1
Role in Hearing: Sound waves create pressure waves in the perilymph of the scala vestibuli. These waves are transmitted through the cochlear duct to the organ of Corti and eventually pass into the scala tympani, where they are dampened at the round window.2