This is how the ear, hearing and balance sense work

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Last Medical Review: April 1, 2020
Medically Reviewed by Dr. Elisabeth Vincent Hamelin
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The ear consists of several different parts. In the inner ear there are both the auditory ear and the balance organ. The different parts of the ear receive and process information about sound and body position. The information is then passed on to the hearing and balance centers in the brain.

In this text you can read about the different parts of the ear and how the hearing and the balance sense work.

Different parts of the ear

The ear consists of three parts:

  • pinna
  • middle ear
  • inner ear.

The outer ear collects sound

The outer ear consists of two parts, the ear mussel and the ear canal.

Pinna

The mussel is the part of the ear that sits outside the body. The mussel consists of cartilage covered with skin. One exception is the eardrum. There is no cartilage there but only a little fat.

The ear canal

The ear canal is surrounded by bones in the inner part and cartilage in the outer part. The skin in the ear canal contains glands that form ear wax.

Eardrum

At the far end of the ear canal is the eardrum. The eardrum consists of connective tissue and is thin and mobile. The sound reaching the eardrum causes the eardrum to start to swing. This allows the sound waves to be passed to the middle ear. The eardrum is sensitive and can crack if the pressure increases sharply. Such pressure can come from outside, for example by a blow to the ear. The pressure can also come from within, for example in the case of ear inflammation. Most often, the eardrum quickly heals itself after an injury.

In the middle ear are the auditory bones

Inside the eardrum is a cavity called the middle ear. In the middle ear there are three hearing bones. The three legs are the hammer, the anvil and the stirrup. The eardrum is attached to the hammer which is attached to the anvil with a joint. The anvil is attached to the riser with a hinge. The riser is then attached to a connective tissue that covers an opening into the inner ear. This opening is called the oval window.

The Eustachian tube

The pressure on both sides of the eardrum needs to be about the same. It is necessary for the eardrum and ear bones to move as usual. The middle ear has contact with the pharynx through a narrow passage called the ear trumpet. This time is normally closed but opens when you swallow and yawn. You can even out the pressure in your ear by holding your nose while blowing. Then you push air into the middle ear through the ear trumpet.

The inner ear

The inner ear consists of the earpiece and the balance organ. These lie inside the bones of the skull.

Hair cells record sounds and balance impressions

Inside the earpiece and the balance organ are sensory cells called hair cells. These are cells with small thin hairs on the surface. The hair cells receive information about sound and balance and pass on the information to the brain through the auditory and balance nerve.

This is how the hearing works

Already at six months a fetus can respond to sounds. The hearing then develops rapidly.

Sound is wave motion

The ear mussel captures the sound found in the surroundings. The sound waves are then led through the ear canal, towards the eardrum. The sound waves cause the eardrum to turn. The movement is transmitted to the inner ear by means of the three auditory legs, the anvil, the hammer and the stirrup. The riser covers an opening into the inner ear called the oval window.

The fluid in the inner ear for the movement continues

In the inner ear there is fluid that moves the movement. In addition to the oval window, there is another opening in the inner ear. This opening is called the round window. The two openings allow the fluid to move in the channels located in the inner ear.

You become aware of the sound as the impulses reach the brain

There are also hair cells in the eardrum. The movement of the fluid causes the hairs on the hair cells to bend. This causes the hair cells to convert the movement into nerve signals. The nerve signals go through the auditory nerve to the auditory center of the brain.

The brain interprets the nerve signals coming through the auditory nerve. Then we become aware of the sound. Since we have two ears, the difference in sound from the different sides can help us to determine where the sound comes from.

This is how the balance organ works

In the ear there is also the balance organ that records the body’s position and movement.

The lime crystals are important for the balance mind

The balance organ contains small crystals of lime. The lime crystals are located on top of the hair cells. The crystals are affected by gravity and move as we move. This allows the hair cells to get information about the body’s position and movement.

Sometimes the position of the crystals can be disturbed. Then you can get so-called crystal sickness, which causes severe dizziness in the change of position. Usually the problems go away by themselves, but sometimes it may be necessary to get the crystals back in the right position.

The hair cells send information to the brain

The nerve impulses that the hair cells send out go through the balance nerve to the brain. You become aware of the body’s movements and position when the impulses reach the center of balance. The brain coordinates information from the inner ear with information from the hearing, vision, skin and from the muscles and joints of the body. Sometimes the brain can get tasks that do not match. Then we feel dizziness and instability.

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