Anatomy & Physiology of the Human Ear

The human ear is a complex system responsible for both hearing and balance. It is composed of the outer, middle and inner ear. All three components control hearing, and the inner ear also controls balance.

Outer Ear

• The outer ear is the pinna (the external ear) and the auditory canal. The shape and function of the pinna is to concentrate sound waves into the auditory canal.

Middle Ear

• The middle ear, situated behind the ear drum, is an air-filled cavity that includes the three ear bones (hammer, anvil and stirrup) and the opening of the Eustachian tube. The middle ear regulates pressure and moves sound to the cochlea.

Inner Ear

• The inner ear is the most complex portion of the ear. It contains the cochlea for hearing and the vestibular system for balance.

How Do We Hear?

• When sound waves enter the auditory canal, they cause the eardrum to vibrate. These vibrations are amplified by the three bones of the middle ear, changed into nerve signals by the cochlea and sent to the brain for interpretation.

Ear Dysfunction

• Given the complexity of the ear, any dysfunction can result in hearing and balance problems. Ear disorders can be caused by disease such as Meniere's (excess fluid in the inner ear) or trauma, either by blunt force or constant exposure to loud noises.