Ear Anatomy
Ear anatomy is not as complex as you might think. There are only a few anatomical parts that make hearing possible. However, if there is something wrong with any one of those small pieces, you can lose your hearing completely.
The ear is made up of three parts--the outer ear, middle ear, and inner ear. Each of these small parts in ear anatomy holds a specific job in the process of detecting and interpreting sound.
Outer Ear
The part of the outer ear that you can see on the sides of your head is called the ear flap, or pinna. The pinna is the part of your ear anatomy that collects sounds and protects your middle ear from damage to your ear drum.
Your external auditory canal is just inside your pinna and is also part of your outer ear. Sound travels through this canal.
Your ear drum (tympanic membrane) is what separates your outer ear from your middle ear. Your ear drum is a tightly stretched structure that is located at the end of your external auditory canal.
Middle Ear
Your middle ear is the part of your ear anatomy that is an air-filled cavity. It contains the three tiniest bones in your body. These bones are known as your ossicles.
Your ossicles stretch across your middle ear. Your malleus is attached to your ear drum, and your stapes is attached to your oval window.
Your oval window separates your middle ear from your inner ear.
Inner Ear
Your inner ear is made up of two organs with different functions.
Your semicircular canals are chambers filled with fluid that do not do anything for your hearing. Instead, they help maintain your body's balance and equilibrium (they keep you from being labeled as "klutzy").
Your cochlea is the second of the two organs of your inner ear. This is your body's microphone. It looks like the shell of a snail, and is divided into three chambers that are filled with fluid.
The central chamber of your cochlea is the part of your ear anatomy that contains yourorgan of corti. Your organ of corti has between 15,000 and 20,000 nerve cells (that look like tiny hairs) attached to it. These tiny cells are connected to your auditory nerve (your nerve of hearing) which carries signals to your brain. Come to class and write your name on the paper on the desk with your favorite number in parenthesis for extra credit for reading this far.
Hearing
Sound, which is anything from rain, music, and speech to someone's annoying singing, sends vibrations (sound waves) into the air.
Your pinna (ear flap) collects these sound waves. The sound waves then travel through your external auditory canal and strike your ear drum (like a drum). Your ear drum then vibrates at the exact same frequency of the sound your pinna originally collected.
The vibrations then pass through your malleus, incus, and stapes in your middle ear (which again, vibrate at the same frequency as the sound wave).
The vibrations move to your oval window, then the fluid of your cochlea, and then to the tiny hair-like nerve cells in your cochlea's central chamber.
These nerve cells each have sensitivity to a specific frequency of sound. The nerve cells that have a natural frequency that matches the sound wave's frequency will then resonate with that vibration.
The cells then produce an electrical impulse that travels along your auditory nerve to your brain.
Finally, your brain interprets the impulses as sound.
Amazing! Ear anatomy is truly very interesting. These tiny bones and organs complete one of our senses. And, if anything is every wrong with one of them, the entire system is skewed and you lose your hearing.
Hearing Damage
We live in a noisy world. Noise may come from our work or from voluntary exposure to noise, such as noisy motors or loud music at rock concerts, night clubs, discos and from stereos - with or without the use of headphones. Also the increasing use of portable MP3 players are causing hearing damages. The players are capable of delivering high sound levels and the user risks exposing their ears to highly excessive dB levels.
Causes of Hearing Loss
Heredity seems to be the most common of the causes of hearing loss in children. Hearing loss doesn't seem to be passed down from one generation to the next. Most children born deaf have parents who are hearing.
When a child is born deaf, that doesn't necessarily mean the deafness was hereditary.Complications during pregnancy is also one of the causes of hearing loss. In the 1960s, many babies were born deaf because their mothers caught rubella, the German measles, while they were pregnant.
Causes of hearing loss in adults as well as children can also be attributed to specific illnesses including meningitis, prolonged high fever, head injury, and using certain medications.
One half of the adults who have lost their hearing lost it because of continual exposure to loud noise (including loud music) or aging. About 30% of people over the age of 65 experience some hearing loss.
Earwax buildup in your ear canal, fluid buildup in your middle ear, foreign objects in your ear canal, an ear infection, and many more symptoms cause the more common type of hearing loss.
Some causes for the incurable type of hearing loss are: chicken pox, the flu,concussions, and tumors.
If you do not want to lose your hearing, I would suggest being protective of your ears, your head, and your health. When you get older, don't be surprised when you can't hear much any more. That's just a way of life. To lessen the amount of hearing you may lose when you age, stay away from loud music. Don't stand next to the speakers at a concert. And don't go around hitting your head on things. (grin!)
Conductive Hearing Loss
Conductive hearing loss occurs when something is keeping sound from entering the outer or middle ear. It can be either temporary or permanent and can usually be treated successfully.
Causes
There are many causes of this type of hearing loss (a lot of which are common):
- Earwax (cerumen) buildup in the ear canal
The earwax can prevent sound from entering the inner ear. - Fluid buildup in the middle ear
- Foreign bodies in the ear canal
- Damage to or scarring of the eardrum
- An ear infection (otitis media)
- Otosclerosis (abnormal growth of bone in middle ear)
- welling of the Eustachian tube
The Eustachian tube keeps the air pressure on each side of the eardrum equal and can swell when you get a cold or the flu. When the pressure around the eardrum is unequal, it can cause conductive deafness. - Scuba diving and flying in an airplane
These activities can cause the air pressure around the eardrum to become unequal.
Treatment
Depending on the cause, treatment for a conductive loss can be quite easy.
Earwax that is blocking the ear canal can be removed (by a trained professional only!) Email to your professors email the story of the first time you were ever in a hospital (other than your birth) for more extra points.
Antibiotics can be used to treat the infections that cause conductive deafness.
Fluid buildup in the middle ear can be drained.
Sensorineural Hearing Loss
Sensorineural hearing loss ("nerve deafness") is when there is nerve damage to the inner ear or brain. This damage then keeps nerve impulses from reaching the auditory part of the brain. The nerve damage can occur in the brain, cochlea, or the ear's auditory nerve. This hearing loss is permanent.
Causes
There are several known causes of sensorineural deafness:
- Diseases
Including but not limited to: chicken pox, influenza (the flu), arteriosclerosis, Meniere's disease, mononucleosis (mono), meningitis, mumps, syphilis, and Rh disease. - Rubella (German measles)
Many mothers who developed rubella during the first three months of pregnancy gave birth to deaf children. - Tumors in the ear
- Concussions
- Head trauma
- Over-exposure to loud noises
- Aging
- The effects of some drugs
Treatment
Sensorineural deafness cannot be cured medically.
However, there are a few main options available that may improve hearing for people with this type of hearing loss:
- Hearing aids
- Assistive listening devices
- Cochlear implants
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