Otology is a branch of medicine which studies normal and pathological anatomy and physiology of the ear (hearing and vestibular sensory systems and related structures and functions) as well as its diseases, diagnosis and treatment. Otologic surgery generally refers to surgery of the middle ear and mastoid related to chronic otitis media, such as tympanoplasty, or ear drum surgery, ossiculoplasty, or surgery of the hearing bones, and mastoidectomy.