The eardrum: an important part of the human ear

The human ear is one of the most delicately constructed organs. In the ear cavity, there are very small details, but they work together very smoothly. One of the important details that help the human ear to receive sound is the eardrum. What is the structure and function of the eardrum? Please see the article below.

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• 1. What is the structure of the eardrum?
• 2. The eardrum and deafness
• 3. Cases affecting the function of the eardrum

1. What is the structure of the eardrum?

1.1. Structure of the eardrum

Eard _ with the bottom of the ear canal. The normal eardrum is translucent, bright white, or slightly pinkish gray. Often, we can see through.

The eardrum is about 9mm (1/4 inch) high and about 8mm (3/8 inch) wide, paper thin but very strong. The eardrum is made up of three layers. The first layer is the skin of the ear canal, located outside. Next, is a layer of stiff yarn. The outermost threads are like the spokes of a wheel. The inner fibers are concentric, spreading out in an enlarged circle. Together, they form an exceptionally strong membrane, which ensures that it does not tear over time under the pressure of water, air, and infection. Finally, the inner layer, called the mucous membrane, is located in the middle ear cavity.

1.2. Tissue and bone associated with the eardrum

In the normal ear, the malleus hangs from the head to a point about two-thirds of the tympanic membrane pointing downward. At the point where the malleus joins the tympanic membrane, the tympanic membrane is pulled toward the middle ear, forming the inner tip of the cone.

The light of the otoscope reflected from the tip of the malleus to the base of the eardrum is called the bright triangle. This bright triangle is present in most normal ears.

The tissue of the lower 4/5 of the tympanic membrane is firm and is called the pars tensa. The upper fifth is soft because of the lack of a fibrous layer called the fascia.

In children, the eardrum is thin and elastic. It will become thicker and firmer as it matures. The annular ring that holds it in place forms a waterproof and sealed membrane between the middle and outer ear.

Structure of the eardrum

1.3. Partition of tympanic membrane

It would be a bit remiss to mention the tympanic membrane without mentioning the partition of the tympanic membrane. The tympanic membrane is divided into 4 parts to make it easier to describe the location in relation to the anatomical parts or the sites of interest.

Given the tympanic membrane is a loop on the side of the head, the longitudinal axis will follow the hammer handle starting at 1 o'clock giving us the anterior and posterior parts. The horizontal axis begins at 4 o'clock, dividing the tympanic membrane into the upper and lower parts.

Segmentation to identify damage, if any. For example, when the eardrum is perforated, it will determine the exact location of the hole so that it can be easily intervened.

Stitch recovery after perforated eardrum

1.4. Function of the eardrum

The vibration of sound, the sound energy, is gradually increased by the auricle and the resonance of the ear canal, making it easier for the eardrum to move back and forth in response to the vibrations. The eardrum is attached to the hammer bone in the middle ear.

To put it more simply, the vibrations of sound waves are picked up by the outer ear flap. That impulse is amplified through the ear canal, inward, vibrating the eardrum. Vibration causes the hammer chain to vibrate and register the impulses. Nerve cells receive those impulses, converting them to sounds that the human ear can perceive and distinguish.

2. The eardrum and deafness

Common types of deafness:

• Conductive Deafness: Due to some inactivity or blockage in the outer or middle ear, which blocks the passage of sound. Most causes of this sound blocking can be resolved with medical treatment.
• Receptive deafness, also known as sensorineural deafness: Due to damage to the inner ear, the sound transmitted to the ear cannot be converted into electrical impulses.
• Mixed Deafness: Due to damage that combines both the outer or middle ear with the inner ear. This type of deafness has both conductive and receptive characteristics.
• CNS Deafness: The brain cannot process, receive, and understand sounds or sentences correctly.
• Non-organic hearing loss: commonly known as functional hearing loss. The disease is mainly due to several psychological causes. There was no damage to the organs involved in the hearing mechanism.

Thus, deafness may or may not be due to the tympanic membrane. If the problem is caused by the eardrum, the hearing loss is conductive or mixed.

>> See more: Is perforation of the eardrum due to trauma dangerous?

3. Cases affecting the function of the eardrum

3.1. Ear malformations

Ear defects that affect the function of the eardrum include:

• Anomalies such as narrowing or absence of the external ear canal.
• Deformed or absent auricle.
• Cauliflower (broccoli) earlobes.

These defects can cause hearing loss. The part of the pinna that cannot absorb the damaged ear canal will cause interference and reflection of sound waves. Makes listening not subtle.

3.2. Due to dirt in the ear (earwax)

Ear plugs are a common cause of conductive hearing loss. Normally, earwax moves out of the external ear canal spontaneously. Sometimes, earwax builds up in the ear canal, forming a plug that partially or completely seals the ear canal.

Earwax is a yellow, brown, or dark red substance if the wax is wet or black if the wax is hard and dry (common in older people).

If the ear canal is only partially blocked, the patient will have normal hearing or only mild hearing loss. If the ear canal is completely blocked, the patient will definitely not hear. Therefore, cleaning earwax should be done regularly. The earwax cleaning we will provide in a separate article to guide people specifically, avoiding damage to the ear canal and eardrum.

When having a hearing test, it is important to clean the ears thoroughly, before having a hearing test or having a hearing aid fitted.

The earwax that covers the eardrum is difficult to move outward and can cause hearing loss before it is removed by the doctor. If you have earwax, you need to see an otolaryngologist for an otoscopy and proper cleaning. Do not try to remove earwax in this case, it is easy to damage the eardrum.

3.3. Skin defects in the ear canal

Skin allergies or dermatitis make the outer ear itchy and painful. The skin of the outer ear canal becomes red and swollen. This condition will not cause hearing loss unless there is a lot of swelling blocking the ear canal. Ear function tests may be performed if the swelling does not block the ear canal.

Otitis externa is an infection that causes swelling of the walls of the outer ear canal. Otitis externa will not cause hearing loss if the swelling does not block the ear canal.

Polyps (tumors) are tissues that grow away from a surface. When a patient has any tumor or abnormal bone growth, the patient should see a doctor. Do not arbitrarily dissect the tumor until it is clear whether the tumor is benign or malignant.

3.4. The problem of aging

Collapse of the outer ear canal is related to the aging process. It is the tissue around the ear canal that weakens and prolapses causing the wall of the ear canal to collapse. The ear cartilage tissue can also be degraded and softer, even saggy.

The tissue flap can partially seal the ear canal or completely seal the ear canal. To observe the ear canal in this case, you can lift the earlobe up and down.

3.5. Perforation or tearing of the eardrum

This is a common disease of the eardrum. Causes can be: ear infection, ear foreign body, ear fracture, near a loud bang, or being hit in the ear.

Small perforations reduce hearing sensitivity by about 10-15 dB. Small holes usually heal in about a few weeks. Larger holes require surgery to patch the eardrum, to seal the hole. When punctured, the internal hammer bone system no longer receives impulses or has poor reception. In the case of complete and prolonged tearing of the tympanic membrane, it may lead to dysfunction of the receptive system of the ear bone system. Therefore, when you suspect a problem with your eardrum, you need to see a doctor immediately to identify the damage and recover in time.

The single dots look like a hole, but they reflect light from the otoscope, like a mirror. These single dots are holes that have healed and are just a thick layer. They are also called "mirror membranes". When you see "mirror film" it means you have been hurt in the past. Thereby also assessing the damage and current influence of the membrane structure.

Eardrum

3.6. Tumor in the ear

A tumor or cholesteatoma that occurs in the middle ear, sometimes breaks through the upper part of the eardrum, and invades the outer ear canal.

If a patient has these symptoms, they should see a doctor immediately. These are usually malignant tumors. Some require radical treatment because these tumors tend to be highly malignant, with the ability to rapidly invade nearby structures.

3.7. The problem of changing the ear structure after surgery

Wide external ear canal after ear surgery. These people often do not have an eardrum or a fibula in the middle ear. The skin of the ear canal can be very sensitive. If the patient does not have an eardrum, it is necessary to consult and agree with the doctor before installing a hearing aid.

Usually, when the hole in the ear heals, or the ear gets infected again and again, the eardrum will scar. This limits movement of the eardrum and can cause mild conductive hearing loss.

All problems with ear surgery, you must go back to the clinic to monitor complications after surgery. That's what needs to be done.

3.8. Tympanosclerosis

Atrial tissue degeneration due to calcium accumulation has a chalky white color. The fibrous eardrum will no longer be soft and vibration will be less sensitive. As a result, you will hear less.

Atrial fibrillation can affect both men and women. However, some suggest that atrial fibrillation is related to aging and genetics. This issue still needs more research before conclusions can be drawn.

3.9. Foreign bodies in the ear canal

Foreign bodies in the ear canal range from earwax, erasers, insects, sprouts to unknown things.

Some insects such as cockroaches, ants, spiders, flies, bees, etc. can mistakenly enter the ear canal when you oversleep. When you try to get us in the wrong way, it can scare them into going deeper, causing discomfort and pain. The best way is to use a piece of adhesive tape, stick it on the outside of the ear, tilt the head to the side of the foreign body and then go to the doctor. If attempted, the insect can sometimes get trapped and die inside the ear canal or even bite or sting the earlobe. Thereby causing more scary infections.

3.10. Some other cases

Watery ears, blood, pus ... whether smelly or not, must ask the patient to see a doctor.

These are signs of otitis media and are often difficult to treat. Prolonged otitis media will, of course, cause perforation of the eardrum. But if the infection is not controlled, it can cause more serious infectious complications.

Purulent discharge in the ear in otitis media

>> See also: Ear: anatomical structure and physiological function

The eardrum is a delicate part of the human ear. They and the skeletal system of the ear help humans perceive the beautiful sounds of the world. Seeing that important function, you need to take care of the eardrum and ear carefully. If there is a problem, you need to see a doctor for examination and treatment immediately to avoid dangerous complications.

Doctor Nguyen Quang Hieu