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Outer ear
A diagram of the anatomy of the human ear:   Brown is outer ear.   Red is middle ear.   Purple is inner ear.
The auricula. Lateral surface.
Details
Identifiers
Latin	auris externa
MeSH	D004431
NeuroLex ID	birnlex_1705
TA98	A15.3.01.001
TA2	6862
FMA	52781
Anatomical terminology

The outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal.^[1] It gathers sound energy and focuses it on the eardrum (tympanic membrane).

This section needs expansion. You can help by adding missing information. (December 2013)

One consequence of the configuration of the outer ear is selectively to boost the sound pressure 30- to 100-fold for frequencies around 3 kHz. This amplification makes humans most sensitive to frequencies in this range—and also explains why they are particularly prone to acoustical injury and hearing loss near this frequency. Most human speech sounds are also distributed in the bandwidth around 3 kHz.^[7]

An important function of the pinna and concha is to selectively filter different sound frequencies in order to provide cues about the elevation of the sound source. The convolutions of the pinna are shaped so that the outer ear transmits more high-frequency components from an elevated source than from the same source at ear level.^[8]

Malformations of the external ear can be a consequence of hereditary disease, or exposure to environmental factors such as radiation, infection. Such defects include:

• A preauricular fistula, which is a long narrow tube, usually near the tragus. This can be inherited as an autosomal recessive fashion and may suffer from chronic infection in later life.^[9]
• Cosmetic defects, such as very large ears, small ears.^[10][11]
• Malformation that may lead to functional impairment, such as atresia of the external auditory meatus^[12] or aplasia of the pinna,^[13]
• Genetic syndromes, which include:
  • Konigsmark syndrome, characterised by small ears and atresia of the external auditory canal, causing conductive hearing loss and inherited in an autosomal recessive manner.^[14]
  • Goldenhar syndrome, a combination of developmental abnormalities affecting the ears, eyes, bones of the skull, and vertebrae, inherited in an autosomal dominant manner.^[15]
  • Treacher Collins syndrome, characterised by dysplasia of the auricle, atresia of the bony part of the auditory canal, hypoplasia of the auditory ossicles and tympanic cavity, and 'mixed' deafness (both sensorineural and conductive), inherited in an autosomal dominant manner.^[16][17]
  • Crouzon syndrome, characterised by bilateral atresia of the external auditory canal, inherited in an autosomal dominant manner.^[18]

The outer ear's cartilage is homologous to the cartilage in gills of amphibians, fishes, and invertebrates such as the horseshoe crab. The extracolumella cartilage of reptiles is likely also homologous.^[20]

• 
  External and middle ear, opened from the front. Right side.

This article incorporates text in the public domain from page 1033 of the 20th edition of Gray's Anatomy (1918)

Media related to Outer ear at Wikimedia Commons