An incision of the mastoid process to enlarge the passage in the nipple-shaped mastoid portion of the temporal bone that extends downward and forward behind the external auditory meatus (opening).

The auditory, or acoustic, meatomastoidectomies consists of two passages in the ear; the external acoustic meatus leads from the auricle to the tympanic membrane (eardrum) and the internal acoustic meatus which is for the passage of nerves and blood vessels.