What Is the Cochlea?

A component of the ear bone labyrinth within the hearing organ is the structure that transmits and feels the sound waves. The cochlea is a spiral bone tube that curls around the snail axis for two and a half weeks. A thin piece of bone protrudes from the center of the snail axial tube, called a bone screw. The outer wall of the cochlea has spiral ligaments.

A component of the ear bone labyrinth within the hearing organ is the structure that transmits and feels the sound waves. The cochlea is a spiral bone tube that curls around the snail axis for two and a half weeks. A thin piece of bone protrudes from the center of the snail axial tube, called a bone screw. The outer wall of the cochlea has spiral ligaments.

The free edge of the bone spiral plate is connected with a flexible fibrous membrane, called the basement membrane, which extends to the opposite side of the bone tube and connects with the spiral ligament. The cochlear canal tube is divided into two parts, the upper part is called the vestibular step, and the lower part is called the drum step. One end of the vestibular steps is a vestibular window, and one end of the drum steps is a worm window. The worm holes of the two parts communicate at the worm top. There is a thin film called vestibular membrane near the bottom of the bone spiral plate. The vestibular membrane, the basement membrane and a part of the spiral ligament form a membranous spiral tube, and the tube is filled with endolymph. The spiral organ (Corti's organ) is an auditory sensor that senses sound wave stimulation. It consists of support cells and hair cells. Hair cells are sound wave sensing cells, and each hair cell forms a synaptic connection with nerve fibers. There is a covering membrane above the hair cells, which is in contact with the cilia of the hair cells. The external sound wave vibrates the cover membrane through the lymph fluid, and the cover membrane touches the hair cells again. Finally, the hair cells are converted into nerve impulses and transmitted to the auditory center through the auditory nerve.

Chinese name

Cochlea

Foreign name

Cochlea

Structure

inner ear

Latin

snail shell

Location

Deep temporal bone

Structure

Conduct and feel sound waves

Tissues and organs around the cochlea

inner ear

It is located in the temporal bone and is composed of a labyrinth of bone and a labyrinth of membrane. The labyrinth of labyrinth is located in the labyrinth of bone. The labyrinth is filled with lymph, the outer labyrinth is between the bone labyrinth and the labyrinth labyrinth, and the inner labyrinth is called the labyrinth labyrinth. The labyrinth is divided into three parts, namely the cochlea, vestibule and semicircular canal. The cochlea is an auditory sensor, and the vestibular and semicircular canals are sensory sensors.

Cochlea: It is a bone tube that circles around the snail axis for two and a half weeks and looks like a snail shell. The interior of this bone tube is divided into upper and lower halves by a bone spiral plate and a basement membrane. The upper half is called the vestibular step and the lower half is called the tympanic step. The vestibular step leads to the middle ear, the vestibular window; the tympanic step leads to the middle ear, another wormhole. At the spiral plate near the basement membrane, there is also a thin film obliquely out to the outer side wall, which is called vestibular membrane. The membranous duct between the vestibular membrane and the basement membrane is called the volute, and is part of the labyrinth. The basement membrane is made of fibers of different lengths connected side by side. The basement membrane fibers at the bottom of the cochlea are shorter and the top fibers are longer. Hair cells are arranged on the basement membrane, which are sound-sensing cells. Each hair cell is connected to a nerve. The hair cell also has a cover membrane. The frequency of sound waves felt by the basement membrane is 20 to 20,000 hertz per second. Sound waves pass through the external ear canal to vibrate the tympanic membrane, and then pass through the activity of the small bones to the vestibular window, causing the external lymphatic vibration in the vestibular step, which in turn causes the vestibular membrane and the internal lymphatic vibration. , Impulse ascending through the cochlear nerve, and then through the midbrain to the medial geniculate body, and finally to the temporal lobe of the cerebral cortex to form hearing. When the outer or middle ear becomes ineffective, sound waves can pass through the skull to the inner ear to produce hearing, which is called bone conduction. But under normal circumstances, bone conduction is not important.

Vestibular and semicircular canals: The vestibule is the middle part of the labyrinth of bone, located between the semicircular canals and the cochlea. There are two communicating membrane sacs, the larger one is called the oval capsule and the smaller one is the balloon. Each of the two capsules has a cyst spot, with hair cells in the cyst spot, and the surface of the cyst spot has calcium crystals called otoliths. When the human body performs a linear motion (acceleration or deceleration) or the position of the head changes, due to inertia and gravity, the otoliths pull and stimulate hair cells, making them excited. Nerve impulses flow into the cerebrum and cerebellum, and reflexes cause postural reflexes to maintain body balance. At the same time, nerve impulses flow into the cerebral cortex to produce a sense of position or a sense of speed. There are three semicircular canals, which are located on three mutually perpendicular planes, each of which is semicircular and opens in the vestibule. Each semicircular canal has a large swelling, called the ampulla, each of which has a bulge, called the ampulla, which has hair cells on it. When the head performs rotational and variable-speed movements, the endothelium stimulates hair cells to excite them. Nerve impulses are introduced into the center through the vestibular nerves. On the one hand, they cause posture reflexes to maintain body balance. On the other hand, nerve impulses enter the cerebral cortex. Causes a sense of rotation. Vestibular and semicircular allergic people, when engaged in linear or rotary variable-speed movements, afferent impulses cause a strong response in the vestibular nucleus and cerebellum, causing postural reflex disturbances and vegetative disorders such as dizziness, nausea, vomiting, sweating and other reactions. This is commonly known as motion sickness and seasickness.