Anatomy of the Ear
The external ear includes the ear outside of the skull (ear lobe, auricle) and the ear canal. Any part of it can become infected, which is called otitis externa. This can lead to problems such as swimmers ear. Cerumen or ear wax impactions can block the ear canal and cause a sense of ear pressure, infection, pain and/or hearing loss. Your Comprehensive ENT physician can evaluate and treat these problems.
The middle ear is the space between the eardrum (or tympanic membrane) and the bone of the skull. It is separated from the ear canal by the eardrum. The middle ear is lined by the same kind of mucous membrane that lines the nose and mouth. The nerve that controls facial movement runs through this space as well. It is connected to the back of the nose by the Eustachian tube. The Eustachian tube is usually closed until swallowing movement pulls it open and allows air to enter the middle ear. Air is needed to equalize the middle ear pressure with the air pressure outside the head. Some people hear this burst of fresh air as a pop or click.
Suspended within the middle ear is a chain of three small bones called the ossicles, which conduct sound vibrations from the eardrum across the middle ear into the fluid-filled inner ear. Inside the inner ear these vibrations turn into nerve impulses and are carried by the hearing nerve to the brain.
The mastoid bone can be thought of as a sinus connected to the middle ear space and thereby connects to the nasal cavity through the Eustachian tube. It is made up of small interconnected air spaces that can be thought of like a honeycomb. It can be involved in chronic ear infections.
The inner ear is located within the bone of the skull deep under the middle ear space. It contains the nerves for hearing and balance. The hearing organ is called the cochlea and the balance organ is called the vestibular labyrinth. The inner ear has two areas that come very close to the middle ear space, the round and oval windows. The oval window is the location where the movement of the ossicles is transmitted to the inner ear fluids. The round window is a membrane that allows the vibrations of the inner ear fluids to occur. When the stapes bone pushes into the inner ear, the round window bulges out to allow the fluids to vibrate. It is in these two areas that middle ear infections can be transmitted to the inner ear and cause nerve damage leading to permanent hearing loss or dizziness. This is rare however. When the inner ear is irritated or inflamed or infected, hearing loss and dizziness can occur.