Auditory meatus

The auditory meatus, also known as the external auditory canal or external acoustic meatus, is a tube running from the outer ear to the middle ear. The human auditory meatus extends from the pinna to the eardrum and is approximately 2.5 centimeters in length and 0.7 centimeters in diameter.

Anatomy

The auditory meatus is divided into two parts: the outer third, which is cartilaginous, and the inner two-thirds, which is bony. The cartilaginous portion is surrounded by the cartilage of the pinna and contains numerous sebaceous glands and ceruminous glands, which produce earwax. The bony portion is narrower and is lined with thin, sensitive skin.

Function

The primary function of the auditory meatus is to transmit sound from the pinna to the eardrum. The shape and length of the canal, particularly the bony portion, help to amplify sounds in the frequency range of human speech. The auditory meatus also protects the eardrum by maintaining a constant humidity and temperature, and by producing earwax, which helps to trap dust and other particles.

Clinical significance

Conditions that can affect the auditory meatus include otitis externa, commonly known as swimmer's ear, which is an inflammation of the external ear and auditory meatus. Other conditions include cerumen impaction, or excessive earwax, and exostosis, which is the formation of new bone on the surface of the bone, often caused by prolonged exposure to cold water.

See also

• Ear
• Middle ear
• Inner ear
• Eardrum
• Otitis externa
• Cerumen impaction
• Exostosis

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