The cochlea, created by three basic chambers, resembles a snail and wraps itself two and a half times around the central bone of the core. At the vestibular window, the first chamber (scala vestibule) reaches to the termination of the cochlea.


The lower chamber (scala tympani) can be traced from the apex to the cochlear window. Perilymph fluid fills each one of these two chambers. These two chambers are considered to be completely separated, however, at the cochlea, they conjoin to be continuous with each other. This special continuation is called the helicotrema.

The middle chamber (cochlear duct) can be found between these two chambers. The cochlear duct is segregated by the top (the vestibular membrane) and the floor (the basilar membrane.)

The middle duct terminates at the helicotrema, but is not part of the helicotrema. The middle duct is filled with endolymph fluid.


Image: Cochlea


The organ of Corti, also known as the spiral organ, exists inside the middle duct. Within the middle duct is the functional organ of hearing, as well, the sound receptors that transform vibrations to nerve impulses. This can be detected along the basilar membrane.

The organ of Corti is coated with epithelium that contains supporting cells, and of course hair cells. The hair cells are embedded into the basilar membrane, while the tops of the hair cells are entrenched in the tectorial membrane. The tectorial membrane secretes a gelatinous coating over the hair cells. This entire chamber becomes a resonating effective chamber for the purposes of transmitting sound impulses to the brain for interpretation.
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