Final answer:
The cochlear membranous labyrinth, or cochlear duct, is about 3 cm long when uncoiled and is involved in the process of hearing by converting mechanical vibrations into neural signals.
Step-by-step explanation:
The cochlear membranous labyrinth, commonly known as the cochlear duct, is a soft wormlike tube approximately 3 cm long if uncoiled. This tube is part of the inner ear structure called the cochlea, which is responsible for converting sound vibrations into electrical signals that the brain can understand as sound. The cochlea itself is a coiled, fluid-filled tube that contains the organ of Corti, the site where sound transduction occurs. The organ of Corti houses mechanoreceptor hair cells that are activated by fluid waves within the cochlear duct. These hair cells have stereocilia that bend in response to vibrations, ultimately leading to the generation of neural signals that are sent to the brain.