Other
Mindspring: Another Ear Infection?
Discusses the location and function of the eustachian tube, which is a key factor in middle ear infections. Includes a diagram of the ear.
University of Illinois
University of Illinois: Mc Kinley Health Center: Eustachian Tube Dysfunction
Describes the eustachian tube, and explains the function of the tube. Diagram, definition, and disease states.
Other
Eastern Illinois University: The Eustachian Tube
Describes the role that the eustachian tube plays in maintaining pressure in the middle ear, during flight in an airplane or other changes in altitude and pressure. Tells why your ears pop more on the descent than on the ascent of a flight.