What is the Middle Ear?

K.C. Bruning

The middle ear is the air-filled central cavity of the ear. It is separated from the external ear by the tympanic membrane, or eardrum, and from the cochlea, or inner ear, by a membrane with an opening in the center called the oval window. It transmits external acoustic sound to the fluid in the cochlea, then makes adjustments so that the change in environment will not dilute the sound. It also helps to provide ventilation to the back of the throat and nose.

The middle ear is the central cavity that is filled with air.
The middle ear is the central cavity that is filled with air.

The tympanic membrane is adjacent to three small bones that together are called ossicles. The hammer-shaped malleus bone is connected to the anvil-shaped incus. The incus is connected to the stirrup-shaped stapes bone, which is the smallest bone in the human body. Together, the three bones are known as the ossicular chain.

Medical help may be required to treat a middle ear infection.
Medical help may be required to treat a middle ear infection.

When sound hits the tympanum, it starts a vibration that reverberates through the ossicular chain. The base of the stapes bone is connected to the oval window membrane. The sound transmitted by the ossicles vibrates through the oval window to the cochlea.

This sequence allows proper transference of sound pressure from the middle ear to the cochlea. It serves as a pressure amplifier for the sound waves. The process allows sound to enter into the fluid environment of the inner ear.

Another key part of middle ear function is the eustachian tube, a tube made of cartilage and membrane that goes from the middle of the ear cavity to the nasopharynx, or the nose and back of the throat. The eustachia tube also provides a place for air pressure to be equalized between the throat and the middle ear. A healthy eustachian tube is the pathway that provides protection and nourishment to all of the structures in the middle ear. The eustachian tube passes through the temporal bone of the skull and reaches to the mastoid lines, which serve as a site for muscle attachment.

Near the nasopharynx, the cells of the eustachian tube are lined with fine hair-like projections called cilia. As the membrane extends through the middle ear, the cells change to a tall columnar structure. After it reaches the mastoid, the membrane is composed of closely packed, cube-shaped cells.

Ventilation is another important function of the middle ear. The eustachian tube opens and closes as needed to allow air into the middle ear cavity. When the dilator tubae muscle is contracted, the tube opens. Improper ventilation can lead to a cleft palate, tumors, neuromuscular defects and craniofacial trauma.

The middle ear is separated from the external ear by the eardrum.
The middle ear is separated from the external ear by the eardrum.

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Discussion Comments


@wavy58 – I went through the same thing last year. Luckily, I found a doctor who knew what to do about the situation.

In order to solve the problem, we had to eradicate the source, which was my allergies. Without taking care of them, we could not get the eustachian tube to go back to normal size and allow the fluid to drain out of my middle ear.

So, after finding out that I had been taking the same allergy medication for years, she told me that my body had become immune to its effects. She said I would have to switch up my medications, and this would keep my body from ignoring the medicine.

I found another allergy prevention medicine, and it helped so much. I could breathe easier, and my ears started to feel better. I was amazed at how much better I could hear after a few days on the new medicine, too.


I have been having problems with fluid in my middle ear for about six months now. It's a vicious cycle that begins with allergies, progresses to a sinus infection, and ends with ear pain.

Although I've taken antibiotics several times over the past few months to clear up the infection, the fluid seems to remain. My eustachian tube is still swollen because of my problems with allergies, so it keeps the fluid trapped in there.

I've been taking an allergy medication every day for a few years now, but it seems to have quit working. Any suggestions for what I can do to get rid of the problem?


@seag47 – My daughter's eardrum burst because of an infection. Her middle ear fluid had gotten so backed up with pressure that it actually tore a hole in the eardrum.

Yellow pus started oozing out of her ear. I took her to the doctor, because she was crying in pain.

The doctor said that the eardrum usually heals itself. He gave her some antibiotic ear drops and some pain medicine.

He also told her to keep her ears dry in the shower by stuffing cotton balls in them. She couldn't go swimming for a few weeks, either.


I had a middle ear infection this summer, and the pain was pretty intense. I had to miss work, because I could not focus on anything other than how much it hurt.

I had been sick for awhile with one cold after another. My doctor told me I had fluid trapped in my middle ear, because the cold had made my eustachian tube swell up.

Bacteria grew in the moist environment, so she gave me antibiotics to clear up the infection. She told me that she has seen cases in which the eardrum bursts because of the infection. Has anyone here ever heard of that?

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