Mastoid, << MAS toyd, >> is one of the five parts of the temporal bone of the skull. It is located at the side of the skull, just behind the ear. The name mastoid means nipple-shaped. This name describes the bottom of the mastoid, which extends downward, forming the mastoid process. The mastoid process may be felt as the hard area just behind and below the ear.
The mastoid process is porous, like a sponge. The pores, or hollow spaces, are called the mastoid cells. They vary greatly in size and number in different individuals. They connect with a larger, irregularly shaped cavity called the tympanic antrum, or cavity. This cavity opens into the middle ear. The mucous membrane of the middle ear extends into the tympanic antrum and the mastoid cells. Infections of the middle ear spread through these connections and may infect the mastoid cells. Doctors call this infection mastoiditis.
Mastoiditis may be serious because the mastoid cells are close to the organs of hearing, to important nerves, to the covering of the brain, and to the jugular vein. A mastoid infection may spread to any of these.
Mastoiditis may result from blowing the nose the wrong way. If both nostrils are held closed when a person blows his or her nose, germs may be forced from the throat into the Eustachian tubes. These tubes link the back of the nose with the middle ear. Antibiotics have cured mastoiditis, but severe cases may require surgery (see Antibiotic).
