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The outer ear includes the auricle and the ear canal. These structures capture sounds and direct them towards the eardrum. Essential for hearing and balance, the outer ear can be subject to infection, trauma and other conditions that can affect hearing health. Find out how to keep this crucial part of your auditory system healthy.
The outer ear consists of the auricle and the external auditory canal. The auricle has a characteristic shape, with considerable variations in size, implantation and form, and consists predominantly of a fibrocartilaginous skeleton covered by skin. On average, it has a major axis of 60-65 mm and a minor axis of 30-35 mm.
In the auricle there are two faces: one lateral and the other medial. On the lateral face there are characteristic reliefs and numerous depressions; the largest of these, the concha, is located approximately in the centre and continues directly into the external acoustic meatus.
The trachus, triangular in shape and located anterior to the concha, also consists of a cartilaginous skeleton covered by skin with piliferous formations, has a protective function with respect to the external auditory meatus and helps to convey sound waves coming from behind the body. The only portion of the auricle without a cartilaginous skeleton is called the lobule or lobe and is located in the lower portion of the auricle.
The outer ear collects sound waves and directs them towards the eardrum membrane. The auricle helps localise the sound source and concentrate sound energy. It is blooded by specific arteries and veins and innervated by branches of the facial and trigeminal nerves.
The external auditory meatus, composed of a fibrocartilaginous and a bony part, extends from the pinna to the middle ear and contains sebaceous glands and ceruminous glands. The glands produce a dense, yellowish substance that, when mixed with sebum and desquamated epithelial cells, forms cerumen, which, under normal conditions, has a protective action. This duct, together with the pavilion, amplifies sounds and protects internal structures. The localisation of sounds is more precise with binaural listening, but is also possible with only one ear.
Diseases of the outer ear, which can cause hearing loss, include congenital or acquired malformations, infections, trauma and tumours. Genetic malformations may involve the external auditory canal, which may be narrowed or absent (atresia), and the pinna, which may be smaller (microtia) or absent (atresia auris).
A common problem is occlusion of the ear canal by a plug of earwax. Cerumen, produced by the sebaceous glands, is normally expelled from the duct by jaw movements and natural cleansing of the skin. However, duct abnormalities, inflammation, or incorrect cleaning with cotton swabs can cause a build-up of earwax, resulting in conductive hearing loss. Foreign bodies may also occlude the duct, requiring their removal with specific instruments, washing, suction, or in complex cases, surgery.
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