Fenestra ovalis

Fenestra ovalis (also known as the oval window) is a membrane-covered opening that leads from the middle ear to the vestibule of the inner ear. It is a key component in the process of hearing, as it allows the transmission of sound waves from the middle ear into the fluid-filled inner ear.

Anatomy

The fenestra ovalis is located in the medial wall of the middle ear, directly opposite the tympanic membrane (or eardrum). It is a small, oval-shaped opening that is covered by a thin, flexible membrane. This membrane is attached to the base of the stapes, the smallest bone in the human body and the final bone in the chain of three ossicles (the malleus, incus, and stapes) that transmit sound vibrations from the eardrum to the inner ear.

Function

The primary function of the fenestra ovalis is to transmit sound vibrations from the ossicles of the middle ear into the fluid of the inner ear. When sound waves cause the eardrum to vibrate, these vibrations are amplified and transmitted through the ossicles to the fenestra ovalis. The movement of the stapes against the membrane of the fenestra ovalis creates waves in the fluid of the inner ear, which in turn stimulate the sensory cells of the cochlea to send nerve impulses to the brain.

Clinical significance

Abnormalities or damage to the fenestra ovalis can result in hearing loss. For example, otosclerosis is a condition in which abnormal bone growth around the fenestra ovalis prevents the stapes from vibrating properly, leading to a conductive hearing loss. Treatment for otosclerosis often involves surgery to replace the stapes bone with a prosthesis, allowing sound vibrations to be transmitted to the inner ear once again.

See also

• Middle ear
• Inner ear
• Ossicles
• Otosclerosis