Middle ear – functions & structure

The middle ear is a central link in the hearing chain. It transmits acoustic stimuli, equalizes pressure differences, and protects the sensitive structures of the inner ear. If its function is impaired, this can have a direct impact on hearing and general well-being. This guide highlights the most important aspects of the anatomy, functions, and diseases of the middle ear.

Anatomy of the middle ear

The middle ear is located between the outer ear and the inner ear. It begins at the eardrum and extends to the oval window opening of the inner ear. This space is called the tympanic cavity and is filled with air.

There are three small, movable bones in the tympanic cavity: the malleus, incus, and stapes. Together, they form the ossicular chain. This chain is lined with mucous membrane and is involved in ventilation and self-cleaning. The tympanic cavity is connected to the nasopharynx via the Eustachian tube (tuba auditiva).

Role of the tympanic cavity

The tympanic cavity is not only an air-filled resonance chamber, but also a buffer against pressure fluctuations. Together with the Eustachian tube, it enables pressure equalization between the middle ear and the outside world. This keeps the eardrum flexible and allows it to transmit acoustic vibrations unimpeded.

Ossicles and sound transmission

The ossicles in the middle ear function like an amplifier system for sound waves.

The hammer is connected to the eardrum and picks up its vibrations. These are transmitted to the anvil, which in turn sets the stirrup in motion. The stirrup transmits the vibrations to the oval window, a membrane that forms the transition to the inner ear. This mechanism enables low-loss transmission of air sound into fluid vibrations in the inner ear.

The function of the Eustachian tube

The Eustachian tube connects the middle ear to the throat. It is normally closed and only opens when swallowing or yawning. This allows air to enter the middle ear, which ensures that pressure is equalized.

In children, the Eustachian tube is still short and tends to run horizontally, which makes them more susceptible to infections. Impaired ventilation can affect the function of the eardrum and increase the risk of middle ear infections.

Common middle ear disorders

The middle ear is a sensitive area that is often affected, especially in children. The most common disorders include:

Acute middle ear infection (acute otitis media)

This usually occurs as a result of an infection of the upper respiratory tract. Bacteria or viruses can enter the middle ear via the Eustachian tube. Symptoms include earache, fever, hearing loss, and a feeling of pressure in the ear.

Chronic middle ear infection

If the acute inflammation does not heal or recurs repeatedly, chronic inflammation may develop. This can cause permanent damage to the eardrum or the ossicular chain.

tympanic effusion

An effusion occurs when fluid accumulates behind the eardrum. This is often caused by a ventilation disorder of the Eustachian tube. Sound can then be transmitted less effectively, leading to temporary hearing loss.

Cholesteatoma (pearl tumor)

This is a benign but invasive growth of skin cells in the middle ear. It can destroy the ossicles and usually has to be removed surgically.

Effects on hearing

The middle ear plays a central role in sound transmission. As soon as this chain is interrupted by disease or mechanical disturbance, it has a direct effect on hearing. Especially in the case of middle ear inflammation or tympanic effusion, the path for sound waves is blocked. The ossicles can no longer move freely, and thus less energy is transmitted to the inner ear.

In these cases, we refer to conductive hearing loss. It can be temporary, for example in the case of infections, or permanent, for example after untreated chronic inflammation. Sound reception is also impaired if the eardrum is damaged. The result is muffled hearing, making it difficult to hear particularly quiet sounds or speech.

In children, recurring middle ear problems are often the reason for delayed speech development. This is because they cannot fully perceive the world acoustically, which affects the processing of speech and sounds in the brain.

Diagnosis and treatment

Whether it is a mild inflammation or a more complex condition, an ENT doctor should be consulted if you have problems with your middle ear. A thorough examination usually begins with an otoscope. This allows the doctor to examine the eardrum and detect any abnormalities in the ear canal.

Tympanometry is often used when tympanic effusion is suspected. This examination measures the pressure in the middle ear and provides indications of ventilation disorders or fluid accumulation.

Treatment depends on the diagnosis:

• Acute middle ear infection: antibiotics, decongestant nasal drops, painkillers
• Ear effusion: Observation or, if persistent, insertion of a tympanostomy tube
• Chronic inflammation or cholesteatoma: surgical repair of the middle ear
• Eustachian tube dysfunction: Physical therapy (e.g., Politzer balloon), surgical procedures

In many cases, timely treatment is crucial to prevent permanent hearing damage. Children with frequent infections in particular should be checked regularly to ensure that their hearing is developing appropriately for their age.

Interaction with the inner ear and brain

The middle ear is more than just a sound amplifier. It is an active link between the outside world and the sensitive inner ear. The mechanical movements that occur in the eardrum are transmitted to the oval window via the ossicular chain. This is where the inner ear begins with its fluid, the perilymph, and with it the conversion into nerve impulses.

These signals are transmitted via the auditory nerve to the brain, where they are interpreted as speech, music, or sounds. If there is a disturbance in the middle ear, the impulse is missing—and with it, the acoustic impression in the brain. This shows how finely tuned the individual components of the auditory system must work together.

The vestibular system, located in the inner ear, is also functionally and spatially closely connected to the middle ear. Certain middle ear disorders, such as cholesteatoma, can therefore also cause dizziness or impaired balance.