Fenestra rotunda

Fenestra rotunda (also known as the round window) is a key structure in the human ear. It is one of the two openings from the middle ear into the inner ear, the other being the fenestra ovalis (oval window).

Anatomy

The fenestra rotunda is located at the base of the cochlea, the spiral-shaped part of the inner ear responsible for hearing. It is covered by a thin, flexible membrane known as the round window membrane. This membrane separates the middle ear from the fluid-filled cochlea.

Function

The primary function of the fenestra rotunda is to allow the fluid in the cochlea to move. When the stapes (one of the three ossicles or tiny bones in the middle ear) pushes on the oval window, it causes the fluid in the cochlea to move. This movement is necessary for the transmission of sound vibrations from the air in the middle ear to the fluid of the inner ear. The round window membrane covering the fenestra rotunda bulges out to allow this fluid movement, ensuring that the pressure in the cochlea remains constant.

Clinical significance

Damage or abnormalities of the fenestra rotunda can lead to hearing loss or other auditory problems. For example, in a condition known as round window niche obliteration, the round window is obscured, preventing the normal movement of fluid in the cochlea and thus impairing hearing.

See also

• Ear anatomy
• Hearing
• Cochlea
• Middle ear
• Inner ear