The cochlea is the hearing part of the inner ear. When sound waves enter the cochlea from the middle ear, the fluid contained in the inner ear vibrates causing tiny sensory hair cells to pick up the movement and trigger an electrical signal in the auditory nerve. It then passes those signals to the brain where they are heard as sound. The cochlea (plural is cochleae) is a spiraled, hollow, conical chamber of bone, in which waves propagate from the base (near the middle ear and the oval window) to the apex (the top or center of the spiral). Rosenthal’s canal or the spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2¾ turns about the modiolus. There are three chambers of cochlea: the so called scala vestibuli, the scala tympani and the scala media. The cochlea is a portion of the inner ear that looks like a snail shell (cochlea is Greek for snail.) The cochlea receives sound in the form of vibrations, which cause the stereocilia to move. The stereocilia then convert these vibrations into nerve impulses which are taken up to the brain to be interpreted. Two of the three fluid sections are canals and the third is a sensitive ‘organ of Corti’ which detects pressure impulses which travel along the auditory nerve to the brain. The two canals are called the vestibular canal and the tympanic canal.
