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Outer ear

outer ear infection, outer ear pain
The outer ear is the external portion of the ear, which consists of the auricle also pinna and the ear canal It gathers sound energy and focuses it on the eardrum tympanic membrane

Contents

  • 1 Structure
    • 11 Auricle
    • 12 Ear canal
    • 13 Muscles
      • 131 Intrinsic muscles
      • 132 Extrinsic muscles
  • 2 Function
  • 3 Clinical significance
    • 31 Surgery
  • 4 References

Structureedit

Auricleedit

Main article: Auricle anatomy

The visible part is called the auricle, also known as the pinna, especially in other animals It is composed of a thin plate of yellow elastic cartilage, covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the ear canal by fibrous tissue Many mammals can move the pinna with the auriculares muscles in order to focus their hearing in a certain direction in much the same way that they can turn their eyes Most humans do not have this ability 1

Ear canaledit

Main article: Ear canal

From the pinna the sound waves move into the ear canal also known as the external acoustic meatus a simple tube running through to the middle ear This tube leads inward from the bottom of the auricula and conducts the vibrations to the tympanic cavity and amplifies frequencies in the range 3 kHz to 12 kHz

Musclesedit

Intrinsic musclesedit

Intrinsic muscles of external ear
The muscles of the auricula
Details
Nerve Facial nerve
Actions Undeveloped in humans
Identifiers
TA A15301001
FMA 52781
Anatomical terms of muscle edit on Wikidata

The intrinsic muscles of the external ear are:

  • The helicis major is a narrow vertical band situated upon the anterior margin of the helix It arises below, from the spina helicis, and is inserted into the anterior border of the helix, just where it is about to curve backward
  • The helicis minor is an oblique fasciculus, covering the crus helicis
  • The tragicus is a short, flattened vertical band on the lateral surface of the tragus Also known as the mini lobe
  • The antitragicus arises from the outer part of the antitragus, and is inserted into the cauda helicis and antihelix
  • The transverse muscle is placed on the cranial surface of the pinna It consists of scattered fibers, partly tendinous and partly muscular, extending from the eminentia conchae to the prominence corresponding with the scapha
  • The oblique muscle also on the cranial surface, consists of a few fibers extending from the upper and back part of the concha to the convexity immediately above it

Extrinsic musclesedit

Auricular muscles
The muscles of the pinna
Auricular muscles in context with the other facial muscles
Details
Origin Galeal aponeurosis
Insertion Front of the helix, cranial surface of the pinna
Artery Posterior auricular artery
Nerve Facial nerve
Actions Undeveloped in humans wiggle ears
Identifiers
Latin Musculi auriculares
TA A15301001
FMA 52781
Anatomical terms of muscle edit on Wikidata

The auricular muscles or extrinsic muscles are the three muscles surrounding the auricula or outer ear:

  • anterior auricular muscle
  • superior auricular muscle
  • posterior auricular muscle

The superior muscles is the largest of the three, followed by the posterior and the anterior

In some mammals these muscles can adjust the direction of the pinna In humans these muscles possess very little action The auricularis anterior draws the auricula forward and upward; the Auricularis superior slightly raises it; and the Auricularis posterior draws it backward

Functionedit

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 kHz2

Clinical significanceedit

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 life3
  • Cosmetic defects, such as very large ears, small ears34
  • Malformation that may lead to functional impairment, such as atresia of the external auditory meatus 5 or aplasia of the pinna, 5
  • 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 manner3
    • Goldenhar syndrome, a combination of developmental abnormalities affecting the ears, eyes, bones of the skull, and vertebra, inherited in an autosomal dominant manner3
    • Treacher Collins syndrome, characterised by dysplasia of the auricle, atresia of the bony part of the autiory canal, hypoplasia of the auditory ossicles and tympanic cavity, and 'mixed' deafness both sensorineural and conductive, inherited in an autosomal dominant manner36
    • Crouzon syndrome, characterised by bilateral atresia of the external auditory canal, inherited in an autosomal dominant manner 6

Surgeryedit

Usually, malformations are treated with surgery, although artificial prostheses are also sometimes used4

  • Preauricular fistulas are generally not treated unless chronically inflamed4
  • Cosmetic defects without functional impairment are generally repaired after ages 6–73

If malformations are accompanied by hearing loss amenable to correction, then the early use of hearing aids may prevent complete hearing loss3

Referencesedit

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

  1. ^ http://wwwlivesciencecom/33809-wiggle-earshtml
  2. ^ Purves, Dale, George J Augustine, David Fitzpatrick, William C Hall, Anthony-Samuel LaMantia, James O McNamara, and Leonard E White 2008 "Chapter 13" Neuroscience 4th ed Sinauer Associates p 317 ISBN 978-0-87893-697-7 CS1 maint: Multiple names: authors list link
  3. ^ a b c d e f g Богомильский, Чистякова 2002
  4. ^ a b c Пальчун, Крюков 2001
  5. ^ a b СЭС 1986
  6. ^ a b Асанов и др 2003

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    Outer ear beatiful post thanks!

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