Scala vestibuli

Scala vestibuli is a part of the cochlea in the inner ear, which plays a crucial role in the process of hearing. It is one of the three fluid-filled passages in the cochlea, the other two being the scala tympani and the scala media.

Anatomy

The scala vestibuli is located above the scala media and extends from the vestibule of the ear to the helicotrema, where it connects with the scala tympani. It is separated from the scala media by the Reissner's membrane and from the scala tympani by the basilar membrane. The scala vestibuli is filled with perilymph, a fluid that is chemically similar to the cerebrospinal fluid that surrounds the brain and spinal cord.

Function

The primary function of the scala vestibuli is to transmit sound vibrations from the stapes, one of the ossicles in the middle ear, to the cochlea. When the stapes moves, it pushes on the oval window, a membrane-covered opening between the middle ear and the scala vestibuli. This movement causes waves in the perilymph, which then travel through the scala vestibuli, across the helicotrema, and down the scala tympani. These waves cause the basilar membrane to move, stimulating the hair cells in the organ of Corti and triggering nerve impulses that are sent to the brain via the auditory nerve.

Clinical significance

Damage or abnormalities in the scala vestibuli can lead to hearing loss or balance disorders. For example, otosclerosis is a condition in which abnormal bone growth in the middle ear causes the stapes to become fixed, preventing it from transmitting sound vibrations to the scala vestibuli. This can result in conductive hearing loss, which can be treated with surgery or hearing aids.