The external ear (also outer ear, auricular region of the head, Latin: auris externa) is the outer part of each ear consisting of the auricle and external acoustic meatus. At the deep end of the external acoustic meatus, separating the external ear from the middle ear, lies the tympanic membrane (eardrum).
The structures of the external ear participate in conducting and focusing sound vibrations to the eardrum and further to the middle ear that carries them to the inner ear.
The auricle of the external ear collects, concentrates, and amplifies sound waves and guides them into the external acoustic meatus. The angulation of the auricle is specific to catch sounds coming from the front more than coming from behind. The external acoustic meatus has two parts - inner and outer parts. The outer part is lined with hairy skin that contains sweat glands and sebaceous glands, which together create earwax. The hairs and earwax work as a protective barrier and disinfectant. The external acoustic meatus experiences a light bend where the outer cartilaginous part joins the bony thin inner part. This formation causes the outer part to go back while the inner part runs forwards. This works as a protective mechanism, so the foreign objects do not reach the tympanic membrane. The tympanic membrane is like a border between the ear canal and the middle ear.
Common external ear disorders
Like every organ in our body, also the external ear can experience problems and disorders. Because the external ear is the first step to collecting sound and guiding it further, external ear disorders sometimes may result in hearing impairment or possible hearing loss. Some of the most common disorders are cerumen impaction, foreign body occlusion, growths, infection, furuncle, and congenital malformations. To treat this, people may have to use softeners and ear irrigation. Too much ear wax can cause external otitis with pain, vertigo, tinnitus.
This situation happens when earwax is accumulated in the ear canal, resulting in impaired sound flow to the tympanic membrane. Even though a small amount of wax is good for our ears, too much wax can cause hearing and balance problems.
This is one of the most common hearing problems in kids because young children like to put small toys and objects in their noses and ears. Unfortunately, this can cause trauma to the ear canal and the tympanic membrane. It is not advised to try and take out deeply put foreign objects at home by parents.
The most common growth on the external ear is exostoses. They are benign, skin-covered bony growths. There are no specific reasons why these may appear, but exostoses are more seen in people who are repeatedly exposed to cold water.
The external ear can also experience infections like external otitis and furuncle. External otitis is usually caused by bacteria known as pseudomonas. Infection can cause pain, swelling, discharge from the ear, itching, and possible hearing loss. External otitis is treated with antibiotics. Furuncle is an infection that starts when a hair follicle is infected. This infection is usually caused by staphylococcus aureus. If furuncle blocks the ear canal, the person can experience hearing loss.
Atresia of the external ear canal can cause hearing loss. In this situation, the ear canal has not developed. Many genetic syndromes affecting other parts of the body can also affect hearing and external ear development like Goldenhar syndrome (affected the development of the eyes, ears, bones of the skull, vertebrae), Treacher Collins syndrome (auricle dysplasia, atresia of the bony part of the external acoustic meatus), Crouzon syndrome (bilateral atresia of the external acoustic meatus). Sometimes surgery and hearing aids may be needed to treat these malformations.