eardrum
definition
The eardrum, also called the tympanic membrane or tympanic membrane (Membrana tympani), is an essential part of the sound conduction apparatus of the human ear and forms the boundary between the external auditory canal and the middle ear.
anatomy
The round to oval eardrum measures around 9-11mm in its longest diameter and is just 0.1mm thick. Its largest part, the pars tensa, is stretched by a ring of fibrous cartilage, which in turn is fused with the bone of the ear canal. However, the eardrum does not form a stretched and straight membrane, but a kind of funnel, the lowest point of which is fused with the tip of the hammer handle. This is even visible from the outside through the thin eardrum. If sound waves hit this funnel, it is made to vibrate and transmits the sound to the inner ear via the ossicles (hammer, anvil and stirrup). This process leads to an amplification of the sound many times over.
When viewed through an otoscope, the eardrum becomes visible as a shiny surface and has a characteristic light reflection. Its color is often called Gray or mother-of-pearl described.
The eardrum is a very sensitive organ. Touch is often perceived as painful and can even be accompanied by nausea and fainting. Various branches of the trigeminal nerve and the vagus nerve, which innervate the eardrum in a sensitive manner, are responsible for this.
Function of the eardrum
The eardrum is a thin membrane that is made up of three layers and is clamped in the ear canal. It separates the external ear canal from the middle ear. This protects the sensitive middle and inner ear from dirt and prevents microorganisms such as bacteria and viruses from entering.
Its far more important function, however, is the transmission of sound waves. When sound waves hit our ears, they are captured by the auricle and passed through the funnel-shaped outer ear canal to the eardrum. This is roughly the size of a one-cent coin for an adult. The sound waves then set the eardrum vibrating, which in turn is transmitted to the ossicles in the middle ear. The eardrum is directly connected to the first bone of the ossicular chain, the hammer. On the other hand, the ossicles are connected to the so-called oval window. This is also a membrane, but many times smaller than the eardrum. The difference in size between the eardrum and the oval window increases the sound pressure. In addition, another obstacle in the path of the sound is overcome. The sound travels in the air up to the eardrum. The inner ear, on the other hand, which actively processes the sound and forwards the information to the brain, contains a liquid. This transition between air and liquid is bridged with the help of the eardrum and the ossicles. Without the ossicles, the eardrum cannot fulfill its function as a sound transmitter and amplifier and vice versa.
As part of an otoscopy, i.e. an examination of the ear with a special light mirror, you can look at the eardrum from the outside and thus draw certain conclusions about its functionality. Usually, a small light reflex, caused by the light on the otoscope, is visible on the eardrum. If this is missing, it means either that the eardrum has been injured or has otherwise lost its elasticity, for example due to an infection. Both of these are usually expressed in the form of a hearing loss in those affected.
Diseases of the eardrum
- Eardrum injuries
Due to its small thickness and its sensitive structure, the eardrum is quite susceptible to injury. Hard objects can cause direct trauma (perforation). Indirect injuries in the form of Tears in the eardrum (Rupture) can occur as a result of blows to the ear or nearby explosions (so-called barotrauma). In this case, sharp pain in the ear, hearing loss and possible bleeding are usually the first symptoms of damage to the eardrum. Since in this case the protective barrier between the outer and middle ear is also damaged, pathogens can get into the tympanic cavity (especially through penetrating water), which in turn leads to otitis media (Otitis media) can lead.
In general, however, perforations of the eardrum show a good tendency towards spontaneous healing. If the healing process takes place without complications, it is assumed that it will take about 4 weeks until the torn eardrum is completely closed. Complicated ruptures can be splinted with a foil by the ear, nose and throat doctor. However, if the ossicles have been injured, permanent hearing loss can occur. In any case, an ENT doctor should be consulted at an early stage.
- Tympanoplasty
If spontaneous healing is not possible, the defect can be closed with a tympanoplasty. This is a surgical procedure that is used to restore the ossicular chain and the eardrum. The body's own tissue is usually used for this, mostly muscle skin (fascia) or cartilage skin of the tragus or auricle. If it is necessary to replace the ossicles, prostheses made of materials such as ceramic or titanium can be used.
Tear of the eardrum
One of the most common diseases of the eardrum is the eardrum perforation, also known as torn eardrum or "hole in the eardrum". There are several causes for a perforation to develop.
First of all, external violence can lead to a crack. These include fractures of the base of the skull and direct blows to the ear. Similar injury patterns result in injuries from explosions or other sudden pressures. For example, uncontrolled, rapid ascent during diving is a sudden application of pressure. Cotton swabs that are inserted too deeply can also cause a hole in the eardrum, which is why their use is not recommended by doctors. However, influences from within can also cause the eardrum to tear. For example, if an effusion forms in the middle ear as part of an otitis media, the pressure on the eardrum can increase so much that it ruptures. In general, the likelihood of a perforation, regardless of the cause, is always higher if the eardrum is already weakened by inflammatory processes.
Contrary to expectations, a perforation of the eardrum is not always noticed immediately. Hearing loss can occur, but it is often mild. It expresses itself through the feeling that noises can only be heard muffled and as if from a great distance. Short-term, sharp pain can occur. However, the level of pain depends heavily on the cause. They are of course much more pronounced if, for example, a blow to the ear has caused other injuries in addition to the torn eardrum, such as a laceration. Minor bleeding may occur. It is also possible that dizziness occurs because the ear is responsible for the sense of balance as well as hearing. In turn, dizziness triggers nausea and vomiting. In summary, the symptoms are mostly unspecific and only rarely allow conclusions to be drawn about the exact cause. For this reason, an ear, nose and throat doctor should always be consulted if such symptoms occur or an eardrum is suspected. Because only a look into the ear with the otoscope can provide precise information. Only in rare cases are hearing tests performed in addition to otoscopy.
Therapy depends on the extent and cause of the perforation. Smaller perforations usually heal on their own and should only be protected from water, dirt and infections during the healing process. If the perforation is massive and the edges of the tear do not lie against each other or the eardrum is already scarred from previous injuries, an operation may be necessary. The hole is either sewn back together directly or a material is added that closes the eardrum like a patch. This patch is either a piece of tissue made artificially from silicone or an endogenous piece of tissue. Since an open eardrum is no longer a protection against infections in the middle ear, an antibiotic is always prescribed prophylactically. If pain is present, a pain medication is prescribed. In addition, it is recommended to shower with caution and not to go swimming during this time. How long exactly a perforation of the eardrum takes to heal cannot be definitively determined. The duration depends heavily on the cause and the associated therapy. Simple perforations that can heal spontaneously take about a week. If, on the other hand, an operation is required, such a disease can drag on for several weeks.
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Eardrum inflammation
An inflammation of the eardrum, also known as myringitis, can be an extremely painful disease of the eardrum. It is often caused by an otitis media spreading to the eardrum. In general, the classic symptoms of inflammation then appear: pain, reddening, overheating and loss of function. The pain is usually already present from the otitis media and in the worst case it can become worse. If a doctor looks into the ear, he will be able to see reddening of the ear canal and eardrum. Usually, the light from the otoscope, which is used to examine the ears, reflects off the eardrum. If there is inflammation, this light reflex is canceled and the doctor sees a dull, reddened membrane. Overheating can be limited to the ear and the auricle or can spread systemically throughout the body. If she does this, one speaks of a fever. Fever is common in children with eardrum inflammation, but less common in adults. Therefore, an eardrum should always be considered if a child develops a fever and the cause is not yet known. The loss of function manifests itself in a hearing loss. The diagnosis can be made by a doctor who looks into the ear through an otoscope and asks about the patient's history.Because an otitis media that spreads to the eardrum is often based on a viral cold.
Usually the middle ear is connected to the throat by a duct. This passage ensures ventilation of the middle ear and ensures that bacteria that have entered the middle ear can be transported out again. If this passage is blocked because of a cold, bacteria can build up in the ear and cause inflammation. Therefore, previous colds should always be reported to the attending physician in order to speed up the diagnosis. A second, but less common cause is an external infection. The bacteria reach the eardrum through the ear canal. However, this only happens when the natural protective mechanisms of the ear canal, small hairs and ear wax, are no longer present. Therefore, the corridor should not be cleaned with cotton swabs and ear plugs should be worn if swimming frequently.
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An inflammation of the ear drum does not have to be treated with medication, because it usually heals on its own after a few days to a week. However, if you experience severe pain, pain relievers such as ibuprofen or paracetamol can be taken. Ibuprofen is also anti-inflammatory, while paracetamol has an antipyretic effect. Depending on the individual symptom constellation, you can choose. In addition, the affected ear should be protected, for example from water, and a certain amount of rest should be observed under certain circumstances. If the bacterial inflammation is particularly persistent, the use of antibiotics can be considered. For this purpose, an ear, nose and throat doctor should be consulted. As a rule, there are no long-term effects, but long-term hearing loss can occur in particularly severe cases.
Ear drum vibrates
It is part of the regular function of the eardrum that it is set in oscillation by sound waves and vibrates. Usually these vibrations are not noticeable. In the context of certain diseases, however, symptoms such as noticeable vibrations, humming and other annoying noises in the ear can occur. Causes can be anatomical malformations, inflammation of the eardrum and middle ear or tinnitus. Sometimes pressure fluctuations can also be a trigger, especially if you have a cold and the mucous membranes are swollen. Because of the swellings, such pressure differences can no longer be balanced out so well and the impression can arise that the eardrum is vibrating with every slightest movement. Except in the case of a cold, an ear, nose and throat doctor should be consulted as early as possible, as symptoms of this type usually only intensify over time. A cold, on the other hand, is usually healed after ten to fourteen days, which is accompanied by a decrease in vibration.
Medical diagnostics
Otoscopes represent a simple and quickly available means of diagnosing possible eardrum or middle ear diseases. They consist of a handle, an ear funnel and a light source, which can be inserted into the ear.
Another diagnostic tool is the Tympanometry represent, with which the function of the eardrum and the Middle ear can be checked. Here, pressure fluctuations are generated just in front of the eardrum, i.e. alternating positive and negative pressures. These are ultimately reflected by the eardrum and registered by a probe. The stiffness or flexibility of the eardrum (the Eardrum compliance) be calculated. The result of this is ultimately what is called Tympanogram, which, for example, makes negative pressures in the middle ear or fluid accumulations in it recognizable.
