Outer ear

Anatomy
The outer ear consists of the skin and cartilage. This outer portion is called the pinna or the auricle. It consists of elastic cartilage covered with skin. As we age, the cartilage becomes less elastic and less flexible.

The external ear canal is also a part of the outer ear. A person’s ear canal is about one inch long, less than ½ inch in diameter, and ends medially (toward the middle) at the eardrum – more appropriately called the tympanic membrane. The outer one-third of the external auditory canal courses through skin and cartilage, but the inner two-thirds of the canal passes through bone to terminate at the tympanic membrane.
Cerumen or “earwax” (and small amounts of oil sebum) is produced by specialized cells in the outer one-third of the canal. (Earwax is normal and desirable in an ear canal. It protects the skin of the canal – which is very delicate – against infectious agents. The secretion of oil helps the canal to expel the wax.)

Damage and Disease
Some babies are born with abnormalities of the external ear or canal. Most common birth problems are lack of a pinna (atresia) and/or a closed external auditory canal (canal stenosis). Children tend to have a lot of cerumen, especially at birth. This abundance of earwax is not harmful and eventually will be naturally expelled.

The most common cause of adult problems in the outer ear canal arises from attempts to clear the ear of cerumen. Efforts to remove the earwax with paper clips, cotton swabs, or other mechanisms should be avoided. In cases where there is an abnormal amount of ear wax, medical intervention should be sought. An otologist or audiologist can determine if the tympanic membrane is intact before the ear canal is washed.

Function
The outer ear is largely vestigial (left over from evolutionary changes) in mammals, although it does provide some sound gathering and filtering functions. If a person were to lose the outer cartilage portion, there would be no obvious change in the ability to hear normally.

The ear canal, with its wax and curving pathway, acts to protect the delicate tympanic membrane from infectious agents and probing fingers (or other objects). The tympanic membrane (which separates the outer from the middle ear), is a thin piece of skin and connective tissue that functions much like the head of a drum, hence the name “eardrum.” Its purpose is to vibrate in response to sound waves (acoustic energy) that enter the external auditory canal. These vibrations, in turn, pass through the structures of the middle ear.