Mastoiditis in adult
One of the most important structures in your inner ear is the mastoid bone. The mastoid must receive air from other parts of the ear, including the eustachian tube , to function properly. Your eustachian tube connects your middle ear to the back of your throat. If an infection develops in your middle ear and blocks your eustachian tube, it may subsequently lead to an infection in the mastoid bone. This serious infection is known as mastoid bone infection of the skull, or mastoiditis. The most common cause of mastoiditis is a middle ear infection that has been left untreated.