Outer Ear: Anatomy, Function, Structure & Related Pathologies

Q: Painful nodule of the auricular pavillon

It involves the skin, the dermis and the underlying cartilage structure. The cause is unknown. It is localised almost exclusively in the upper part of the pavilion and is painful both spontaneously and on palpation. Treatment is surgical.

Q: Acute external otitis

Inflammation of the ear canal that may be circumscribed (in the form of a pimple) or diffuse and also affect the tympanic membrane. The causes of external otitis can be many: bacteria, viruses, mycetes, traumatic events, etc. Therapy involves cleaning the ear canal by suction, analgesic anti-inflammatory drugs and antibiotic therapy.

How the outer ear works

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.

Anatomy of the outer ear

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.

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What is the function of the outer ear?

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.

Common infections of the outer 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.

Painful nodule of the auricular pavillon

It involves the skin, the dermis and the underlying cartilage structure. The cause is unknown. It is localised almost exclusively in the upper part of the pavilion and is painful both spontaneously and on palpation. Treatment is surgical.

Perichondritis

Diffuse infection of the periocondrium of the pinna that may follow trauma, haematoma, skin infection of the duct, or be a complication of surgery ( tympanoplasty).

Ramsay-Hunt Syndrome

It is caused by the herpes zoster virus. It is characterised by the presence of blisters on the pinna and duct with discrete pain. Sensorineural hearing loss and vertigo may be associated with it. Treatment is with antiviral drugs.

Acute external otitis

Inflammation of the ear canal that may be circumscribed (in the form of a pimple) or diffuse and also affect the tympanic membrane. The causes of external otitis can be many: bacteria, viruses, mycetes, traumatic events, etc. Therapy involves cleaning the ear canal by suction, analgesic anti-inflammatory drugs and antibiotic therapy.

Ear canal mycoses

These are sustained by various species of fungi. Usually saprophytic mycetes are present in the ear canal: personal predisposing conditions (poor hygiene) or environmental conditions (humidity, swimming pool) can favour the onset and development of pathogenic forms. Therapy involves washing the ear canal (with intact membrane) with a 2% boric acid solution and the use of antifungal drugs locally and, in the more resistant forms, systemically.

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