The middle ear consists of the eardrum (tympanic membrane) and an air-filled chamber containing a chain of three bones (ossicles) that connect the eardrum to the inner ear (see Middle Ear). The middle ear amplifies sound, whereas the inner ear changes mechanical sound waves into an electrical signal that is sent to the brain via the nerve of hearing (vestibulocochlear or auditory nerve).
Middle and inner ear disorders cause many of the same symptoms, and a disorder of the middle ear may cause an inner ear disorder and vice versa.
Middle ear disorders may occur because of
Infection (such as acute otitis media, chronic suppurative otitis media, myringitis, or mastoiditis)
Blockage of the eustachian tube (which connects the middle ear and the back of the nose)
Injury (such as eardrum perforation, barotrauma, or objects in the ear)
Doctors usually base the diagnosis on people's symptoms and the physical examination. Doctors examine the ear canal and eardrum with an otoscope (a handheld light used to look at the ear canal and eardrum) and often do hearing tests. Doctors also examine the nose and upper and middle parts of the throat for infections, allergies, and tumors.
CAIA IMAGE/SCIENCE PHOTO LIBRARY
A Look Inside the Ear
