The ear is the organ of hearing and balance. It has three parts: the outer, middle, and inner ear.
- The outer ear collects sound waves, which move through the ear canal to the tympanic membrane, commonly called the eardrum.
- When incoming sound waves strike the tympanic membrane, it vibrates like a drum, and converts the sound waves into mechanical energy.
- This energy echoes through the middle ear. The middle ear is a complex structure filled with air that surrounds a chain of three tiny bones. These bones vibrate to the rhythm of the eardrum and pass the sound waves on to the inner ear.
- The inner ear is filled with fluid. Here, hair-like structures stimulate nerves to change sound waves into electrochemical impulses that are carried to the brain, which senses these impulses as sounds.
- The inner ear also contains three semi-circular canals that function as the body's gyroscope, regulating balance.
- The Eustachian tube, an important structure in the ear, runs from the middle ear to the passages behind the nose and the upper part of the throat. This tube helps equalizes the air pressure in the middle ear to the outside air pressure. Problems here are primary factors in most cases of ear infection.
Middle Ear Infections (Otitis Media) in Children
Acute Otitis Media (AOM). An inflammation in the middle ear is known as "otitis media." AOM is a middle ear infection caused by bacteria that has traveled to the middle ear from fluid build-up in the Eustachian tube. AOM may develop during or after a cold or the flu.
Review Date: 05/03/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.