Picture of Ear
The ears and the auditory cortex of the brain are used to perceive sound. The ear is composed of the outer ear, middle ear, and inner ear. Each section performs distinct functions that help transform vibrations into sound.
The outer ear is made of skin, cartilage, and bone. It is also the site of the opening to the ear canal. A structure called the eardrum (tympanic membrane) lies at the end of the ear canal. The eardrum separates the outer ear from the middle ear. The ear canal contains protective hairs and ear wax (cerumen).
The middle ear (tympanic cavity) lies behind the eardrum. The middle ear contains three small bones (ossicles) that transmit sound waves from the eardrum to the inner ear. The three bones are called the malleus, the incus, and the stapes. The Eustachian tube connects the middle ear to the back of the nose. The Eustachian tube maintains the appropriate pressure in the middle ear that is necessary to transfer sound waves.
The inner ear contains the structures necessary for hearing and balance. The cochlea is the spiral shaped cavity that turns vibrations into nerve impulses that the brain perceives as sound. The vestibule and semicircular canals contain receptors that relay information about position and movement to the brain. This information is used to maintain balance.
Text References: "Anatomy and Physiology of the Ear." Stanford Children’s Health. "Anatomy of the Ear." University of California Irvine.