The human ear is divided into the outer ear, the middle ear and the inner ear, and in the inner ear, there is a structure like a snail shell, that is, the cochlea. So, as a component of the human ear, what is the structure of the cochlea, and what is its role?
As an anatomy of the inner ear, the cochlea, together with the vestibular labyrinth, forms the inner ear bone labyrinth, which is a structure that conducts and senses sound waves. The name cochlea comes from the similarity of its shape to the snail shell, and the English name of the cochlea is the Latin word for "snail shell". The cochlea is an integral part of the peripheral auditory system. Its core part is the Corti apparatus, which is composed of hair cells and support cells, etc., which is an auditory transduction organ responsible for converting the sound signals from the middle ear into corresponding nerve electrical signals, which are handed over to the central auditory system of the brain for further processing and finally achieve hearing.
Structure of the cochlea:
1. The human cochlea consists of a bony cochlear tube coiled around a tapered worm shaft for 2.5 to 2.75 weeks. Assuming that the bony cochlear canal is straightened, it is easier to understand the relationship between the vestibular, intermediate (membranous cochlear) and tympanic order in the bone cochlea. The membranous cochlear duct is a blind tube filled with endolymphs; the vestibular and tympanic steps are filled with exolyphthalm, which communicate with each other through the cochlear hole at the top of the cochlea.
2. The receptors of sound waves, the Corti apparatus, are located on the basement membrane. The tip of the cilia of the outer hair cells of the Corti apparatus is embedded in the lid membrane, while the cilia of the inner hair cells may not have direct contact with the lid membrane.
3. The medial end of the basement membrane is attached to the bulging lip of the bone spiral plate, while the inner lateral end of the cover membrane is attached to the vestibular lip of the bone spiral plate, so the movement axis during vibration is different.
4. The length of the human basement membrane is about 31.5mm, but its width gradually widens from the base of the cochlea to the parietal periphery of the cochlea. The width of the basement membrane at the near-stapes is about 0.04 mm, and the width of the cochlear hole is about 0.5 mm.
5. The length of hair cells gradually lengthens from the base of the cochlea to the parietal periphery of the cochlea, so the mass of the Corti apparatus can increase with the increase of hair cell length.