The auricle is the external component of the ear that collects and amplifies sound
The auricle (pinna) is the oval appendage that projects from the lateral surface of the head. The characteristic shape of the auricle is determined by an internal supporting structure of elastic cartilage. Thin skin with hair follicles, sweat glands, and sebaceous glands covers the auricle. The auricle is considered a nearly vestigial structure in humans, compared with its development and role in other animals. However, it is an essential component in sound localization and amplification.
The external acoustic meatus conducts sounds to the tympanic membrane
The external acoustic meatus is an air-filled tubular space that follows a slightly S-shaped course for about 25 mm to the tympanic membrane (eardrum). The wall of the canal is continuous externally with the auricle. The wall of the lateral one third of the canal is cartilaginous and is continuous with the elastic cartilage of the auricle. The medial two thirds of the canal is contained within the temporal bone.
The lateral part of the canal is lined by skin that contains hair follicles, sebaceous glands, and ceruminous glands, but no eccrine sweat glands. The coiled tubular ceruminous glands closely resemble the apocrine glands found in the axillary region. Their secretion mixes with that of the sebaceous glands and desquamated cells to form cerumen, or eariuax. The cerumen lubricates the skin and coats the meatal hairs to impede the entry of foreign particles into the ear. Excessive accumulation of cerumen can plug the meatus, however, resulting in conductive hearing loss. The medial part of the canal located within the temporal bone has thinner skin and fewer hairs and glands.
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