Ear Anatomy, Hearing Loss, and Common Ear Disorders

The ear converts sound waves into nerve signals and also helps the body detect position and movement. Knowing where a problem occurs lets you predict the type of hearing loss and the findings on assessment. The outer ear consists of the pinna and external auditory canal. The pinna collects sound, while the canal directs it toward the tympanic membrane. Cerumen helps protect the canal, but impacted cerumen, a foreign body, swelling, or infection can block sound before it reaches the middle ear. The middle ear begins at the tympanic membrane and contains the malleus, incus, and stapes. These ossicles transmit and amplify vibration toward the oval window of the inner ear. The eustachian tube connects the middle ear with the nasopharynx. It opens intermittently to equalize pressure and helps clear fluid. When it is swollen or poorly functioning, negative pressure and fluid accumulate behind the tympanic membrane. This is the mechanical setting for otitis media. The inner ear contains the cochlea, where hair cells transform vibration into neural impulses, and the vestibular apparatus, which contributes to balance. The semicircular canals...