The external parts of the ear give rise to the canal called the external auditory canal. There are often hairs growing near the outer part. As with the nose, these form a purely protective device to keep foreign material and debris from entering the canal, and damaging the drum located at its far end.
The canal is lined with skin, and this is abundantly provided with wax producing glands. Once more this is a protective function devised by nature to trap and engulf any potentially dangerous invaders from touching the sensitive drum that is vital to good hearing.
The drum forms the outer part of the next part of the car system, called the middle ear. The middle ear is really a cleft containing several important structures. It is called the malleus, and in turn this is connected to the incus and stapes. Three small bones conduct soundwaves in the middle ear. At top left is the malleus (hammer), which strikes the incus (anvil), which is joined to the stapes (stin-up).
Ossicles play a major part in the sense of hearing, and convey vibrations from the drum through a series of joints to a hole termed the oval window, which in turn makes contact with the structures of hearing contained in the next part of the ear, the internal ear.
Entering the lower part of the middle ear is the internal entrance of the Eustachian tube coming from the nasopharynx. High in the back wall of the middle ear is the aditus, leading into the mastoid antrum, the hard, bony prominence felt behind the ear. In preantibiotic days this was a common area for serious infections, and many operations were carried out, leaving gaping unattractive scars. Many older persons well remember the horrors of the mastoid operation. But since the advent of penicillin and the other modern antibiotics, such infections and operations are now a rarity.
The middle ear is close to the jugular vessels below, and in very close proximity to the brain above. It is extremely prone to infections and, due to its association with important and potentially dangerous structures, if infected; any trouble here demands immediate attention as a matter of urgency. The third part of the ear is called the inner ear, and this consists of a bony capsule within which is embedded the membranous labyrinth.
Occasionally there may be birth defects in the development of the ear. As the various parts are developed at different times, it may be possible to have one part severely deformed, yet the remainder of the ear apparatus to be functioning normally.
Sometimes the visible outer part of the ear may be small, partly deficient, or have abnormal parts present. As these deformities have a genetic basis, a check must be made for other probable genetic disorders in the opposite ear or other parts of the body. Rubella during the mother’s early pregnancy, or the use of drugs during the first few months, may have played a part. However, with the universal awareness of the potential risks of both of these, the likelihood is lessening every day.
Treatment of deformities lays in either prosthetics or various reconstruction operations.
Injuries to the external ear are common in rough-contact sports, football, boxing etc. Repeated injury may produce bleeding beneath the skin, and resulting deformity may occur in due course unless treatment is given at the time. Treatment will depend on the nature of the injury, but in major haemorrhages beneath the skin may involve aspiration of the blood.
The cars are a common place for skin cancers caused by exposure to the sun in Australia, particularly in those with outdoor occupations. These are usually removed. It is common to see farm workers with large portions of their ears missing due to progressive surgery.