Talk about the structure of the ear and the function of each structure. Thank you ~ ~!

Anatomically, the ear consists of three parts: the outer ear, the middle ear and the inner ear. The external ear includes: auricle: Auricle has the function of gathering and reflecting waves. External auditory canal: 2.5-3.5CM long, composed of cartilage and bone, of which cartilage accounts for about 65,438+0/3. There are two strictures in the external auditory canal, one is the junction of bone and cartilage, and the other is that the distance between bone and tympanic membrane is about 0. At 5CM, the latter is called isthmus of external auditory canal, and the external auditory canal is S-shaped. There is little subcutaneous tissue in the external auditory canal, and the skin is almost attached to the perichondrium and periosteum, so when the infection is swollen, it is easy to cause nerve endings to be compressed and cause severe pain. Cartilage skin contains cerumen glands similar to sweat glands, which can secrete cerumen and are rich in hair follicles and sebaceous glands. Nerves and blood vessels of the external auditory canal: one is the ototemporal branch of mandibular nerve, which is distributed in the first half of the external auditory canal, so it can spread to the external auditory canal when there is pain such as odontopathy; One is the auricular branch of the vagus nerve, which is distributed in the second half of the external auditory canal, so it can cause reflex cough when it is used to stimulate the skin of the external auditory canal. The other is the auricular nerve and occipital nerve from the cervical plexus, as well as the branches from the facial nerve and glossopharyngeal nerve. The middle ear includes: the tympanum: the tympanum is an air-containing cavity located between the eardrum and the inner ear side wall. There are ossicles, muscles and ligaments in the tympanic cavity, and the cavity is covered by mucosa. The outer wall of the tympanic cavity is the tympanic membrane. Eustachian tube: the tube connecting the tympanum and nasopharynx, with a total length of about 35MM for adults. The external 1/3 is bone and 2/3 is cartilage. The external 1/3 internal pharyngeal orifice is located in the lateral wall of nasopharynx. The tympanic orifice of the adult eustachian tube is about 2-2.5CM higher than the pharyngeal orifice, and the tympanic orifice of the child is nearly horizontal, with short lumen and wide inner diameter. Therefore, children's pharyngeal infection is easily introduced into the tympanic cavity through this tube. Tympanic sinus and mastoid inner ear include vestibular semicircular canal, cochlea, internal auditory canal, cranial fossa and petrous part of temporal bone, and auditory and balanced receptors are located in the ear. The human ear can be divided into three parts: the outer ear, the middle ear and the inner ear, including the ear shell and the auditory canal. The human ear shell can't rotate, and it is not as effective as other mammals in identifying the direction of sound and collecting sound waves (mammals can usually rotate the ear shell to collect sound). There are secretions of fat glands in the ear canal and hairs on the inner wall of the ear canal, both of which can prevent foreign bodies from entering the ear. There is a thin film at the junction of the middle ear and the ear canal, called the eardrum. Sound waves from the outer ear can vibrate the eardrum. The middle ear is a small cavity with three small bones across it. These three bones are malleus, incus and stapes in turn, which are connected back and forth. After the sound wave from the outer ear vibrates the eardrum, it can be transmitted to the inner ear through three small bones. There is air in the middle ear cavity, and there is an eustachian tube under it that communicates with the pharyngeal cavity. The communication between the eustachian tube and the pharyngeal cavity is usually closed, but it will open when chewing or swallowing, allowing air to enter the middle ear; To balance the pressure inside and outside the eardrum. The closure of the eustachian tube can prevent your own voice from entering the ear directly from the throat through the eustachian tube, otherwise the sound chamber is too large. If bacteria enter the middle ear from the eustachian tube, it will cause otitis media. There is also a membrane at the junction of the inner ear and the middle ear, and the stapes of the middle ear is connected with this membrane. The inner ear is a complicated and tortuous pipe, so it is also called getting lost. The canal is divided into cochlea, vestibule and three semicircular canals, which are filled with lymph. Cochlea is related to hearing, vestibule and semi-rigid camp are related to balance. There are auditory receptors in the cochlea, and the vibration of sound waves from the middle ear will make the lymph in the cochlea vibrate, thus stimulating the auditory receptors to produce impulses, which will be transmitted to the cerebral cortex by the auditory nerve to produce hearing. The three semicircular canals are perpendicular to each other and located in three different planes. No matter how the head rotates in any direction, at least one semicircular canal will be stimulated by lymphatic vibration and produce impulses, which will be transmitted from the auditory nerve to the brain, and there will be a feeling of head rotation, which is the sense of balance. Humans are used to moving on airplanes. If the semicircular canal is stimulated abnormally when the body moves up and down, such as sailing on a bumpy sea, you will feel seasick. The semicircular canal produces a sense of balance when the head rotates, which is a sense of dynamic balance; The vestibule, on the other hand, produces the feeling of head position when the head is still, which is a sense of static balance. For example, if a person turns his head upside down, that is, stimulates the vestibule, and its impulse is transmitted to the brain, there will be a feeling that the head position is different from peacetime. Ears are very important, so be sure to protect them! Limited hearing range Our human hearing range is limited. Sound waves are measured in hertz. The frequency range of human speech is 500 ~ 3000 Hz. Most young people's hearing range is 20 ~ 20000 Hz. This range is much smaller than dogs and bats. People's hearing range will become smaller and smaller after middle age. Therefore, most elderly people will lose their hearing. Ears can keep the balance of the body. Our ears can help us keep our balance. Each ear has three semicircular canals filled with liquid. When the head moves, the liquid flows, and the receptor sends a signal to the brain that the position of the head changes. Then the brain gives instructions to ensure the balance of the body. Why do people's ears move? Why do some people's ears move? It evolved from animals step by step. Like animals, people have an auricular muscle behind their ears, which can move under the control of nerves. It's just that some people's ear muscles degenerate and their ears won't move; Some people don't degenerate when they move their headphones, so their ears will move. Ears move. This is natural. I didn't grow up later. With a little genetic factor. Biology has proved that it is congenital and a manifestation of developed cerebral cortex. Cranial nerves are stronger, often with stronger willpower and insight. Protect the hearing of teenagers and adults. First, workers who work in noisy environment for a long time should wear protective earmuffs; Second, try not to use walkman or less, especially to avoid excessive volume; Third, stay away from or avoid setting off large fireworks and firecrackers to prevent noise deafness; Fourth, sudden tinnitus and deafness on one side should not be taken lightly, and an otologist should be invited immediately to avoid delaying the best treatment opportunity; Five, there is wax embolism in the ear canal, which should be taken out by a specialist in the hospital. In addition, patients with presbycusis should go to hospitals with good conditions for examination and choose appropriate hearing AIDS to improve their quality of life. If you use MP3 or Walkman, please introduce the correct usage here. Note the following points: 1. Choose headphones with good quality, low noise and adjustable volume, which can be adjusted in time in case of excessive noise; 2. It is best to control the sound intensity of music below 80 decibels, so as to feel comfortable and happy; 3. Listening time with headphones should not be too long.