Anatomy of cochlea and round window

One of the most important functions of the ear is sound recepction, particularly the detection of amplitude and frequency of the sound waves by Corti's organ. The latter is a sensory structure located in the cochlear duct (middle scale), consisting of hair cells lying above the basilar membrane. The cochlear duct is surrounded by two cavities containing perilymph: the scala vestibularis and the scala tympani. The sound reception mechanism involves several other components of the ear such as malleus, incus and stapes, in the tympanic cavity, and the oval and round windows. The movement of the stapes on the oval window, that is adjacent to the scala vestibularis, generates pressure waves in the perilymph along the vestibular canal. The round window, that separates the scala tympani from the tympanic cavity, moves to compensate for oval window movements. The malfunction of the inner ear, due to specific diseases, could be corrected by use of the drugs such as gentamicin that reaches the cochlea through the round window. This brief paper reviews the main anatomical knowledge on the inner ear, with particular attention to the structures of interest for otolaryngologists treating ear disorders by inoculation of drugs into the tympanic cavity.