Outer ear

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Outer ear
Anatomy of the Human Ear.svg
A diagram of the anatomy of the human ear:
  Brown is outer ear.
  Red is middle ear.
  Purple is inner ear.
Gray904.png
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).

Contents

Structure

Auricle

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. [2]

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.[ citation needed ]

Auricular muscles

Intrinsic muscles

Intrinsic muscles of external ear
Gray906.png
The muscles of the auricula
Details
Nerve Facial nerve
Actions Undeveloped in humans
Identifiers
MeSH D004431
NeuroLex ID birnlex_1705
TA98 A15.3.01.001
TA2 6862
FMA 52781
Anatomical terms of muscle

The intrinsic auricular muscles 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.

The intrinsic muscles contribute to the topography of the auricle, while also function as a sphincter of the external auditory meatus. It has been suggested that during prenatal development in the womb, these muscles exert forces on the cartilage which in turn affects the shaping of the ear. [3]

Extrinsic muscles

Auricular muscles
Gray906.png
The muscles of the pinna
Gray378.png
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 Subtle auricle movements (forwards, backwards and upwards)
Identifiers
Latin musculi auriculares
MeSH D004431
NeuroLex ID birnlex_1705
TA98 A15.3.01.001
TA2 6862
FMA 52781
Anatomical terms of muscle

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

The superior muscle 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. The superior auricular muscle also acts as a stabilizer of the occipitofrontalis muscle and as a weak brow lifter. [4] The presence of auriculomotor activity in the posterior auricular muscle causes the muscle to contract and cause the pinna to be pulled backwards and flatten when exposed to sudden, surprising sounds. [5]

Function

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. [6]

Clinical significance

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

Surgery

Usually, malformations are treated with surgery, although artificial prostheses are also sometimes used. [9]

If malformations are accompanied by hearing loss amenable to correction, then the early use of hearing aids may prevent complete hearing loss. [17]

Additional images

Related Research Articles

<span class="mw-page-title-main">Anotia</span> Medical condition

Anotia describes a rare congenital deformity that involves the complete absence of the pinna, the outer projected portion of the ear, and narrowing or absence of the ear canal. This contrasts with microtia, in which a small part of the pinna is present. Anotia and microtia may occur unilaterally or bilaterally. This deformity results in conductive hearing loss, deafness.

<span class="mw-page-title-main">Facial nerve</span> Cranial nerve VII, for the face and tasting

The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue. The nerve typically travels from the pons through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen. It arises from the brainstem from an area posterior to the cranial nerve VI and anterior to cranial nerve VIII.

Articles related to anatomy include:

<span class="mw-page-title-main">Ear</span> Organ of hearing and balance

An ear is the organ that enables hearing and body balance using the vestibular system. In mammals, the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.

<span class="mw-page-title-main">Auricle (anatomy)</span> Visible part of the ear that is outside the head

The auricle or auricula is the visible part of the ear that is outside the head. It is also called the pinna, a term that is used more in zoology.

<span class="mw-page-title-main">Conductive hearing loss</span> Medical condition

Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss, it is referred to as a mixed hearing loss. Depending upon the severity and nature of the conductive loss, this type of hearing impairment can often be treated with surgical intervention or pharmaceuticals to partially or, in some cases, fully restore hearing acuity to within normal range. However, cases of permanent or chronic conductive hearing loss may require other treatment modalities such as hearing aid devices to improve detection of sound and speech perception.

Otoplasty is a procedure for correcting the deformities and defects of the pinna, whether these defects are congenital conditions or caused by trauma. Otoplastic surgeons may reshape, move, or augment the cartilaginous support framework of the pinna to correct these defects.

<span class="mw-page-title-main">Ear canal</span> Tube running from the outer ear to the middle ear

The ear canal is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about 2.5 centimetres (1 in) in length and 0.7 centimetres (0.3 in) in diameter.

<span class="mw-page-title-main">Auriculotemporal nerve</span> Branch of the mandibular nerve

The auriculotemporal nerve is a sensory branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to parts of the external ear, scalp, and temporomandibular joint. The nerve also conveys post-ganglionic parasympathetic fibres from the otic ganglion to the parotid gland.

<span class="mw-page-title-main">Microtia</span> Medical condition

Microtia is a congenital deformity where the auricle is underdeveloped. A completely undeveloped pinna is referred to as anotia. Because microtia and anotia have the same origin, it can be referred to as microtia-anotia. Microtia can be unilateral or bilateral. Microtia occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It may occur as a complication of taking Accutane (isotretinoin) during pregnancy.

<span class="mw-page-title-main">Tympanic cavity</span> Small cavity surrounding the bones of the middle ear

The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound.

Hearing loss with craniofacial syndromes is a common occurrence. Many of these multianomaly disorders involve structural malformations of the outer or middle ear, making a significant hearing loss highly likely.

<span class="mw-page-title-main">Antitragicus</span> Muscle of the outer ear

The antitragicus is an intrinsic muscle of the outer ear.

<span class="mw-page-title-main">Transverse muscle of auricle</span> Muscle of the outer ear

The transverse muscle of auricle is an intrinsic muscle of the outer ear.

<span class="mw-page-title-main">Helicis minor</span> Muscle of the outer ear

The Helicis minor is a small skeletal muscle. The helicis minor is an intrinsic muscle of the outer ear. The muscle runs obliques and covers the helical crus, part of the helix located just above the tragus.

<span class="mw-page-title-main">Anterior auricular branches</span>

The anterior auricular branches of the superficial temporal artery are distributed to the anterior portion of the auricula, the lobule, and part of the external meatus, anastomosing with the posterior auricular. They supply the external acoustic meatus and the visible part of the ear.

<span class="mw-page-title-main">Outline of human anatomy</span> Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

<span class="mw-page-title-main">Posterior auricular muscle</span> Muscle that pulls the ear upward and backward

The posterior auricular muscle is a muscle behind the auricle of the outer ear. It arises from the mastoid part of the temporal bone, and inserts into the lower part of the cranial surface of the auricle of the outer ear. It draws the auricle backwards, usually a very slight effect.

<span class="mw-page-title-main">Superior auricular muscle</span> Muscle that draws the auricle of the outer ear upwards

The superior auricular muscle is a muscle above the auricle of the outer ear. It originates from the epicranial aponeurosis, and inserts into the upper part of the medial surface of the auricle. It draws the auricle upwards.

<span class="mw-page-title-main">Anterior auricular muscle</span> Muscle connectingthe epicranial aponeurosis to the helix of the ear

The anterior auricular muscle, the smallest of the three auricular muscles, is thin and fan-shaped, and its fibers are pale and indistinct. It arises from the lateral edge of the epicranial aponeurosis, and its fibers converge to be inserted into a projection on the front of the helix.

References

PD-icon.svgThis article incorporates text in the public domain from page 1033 of the 20th edition of Gray's Anatomy (1918)

  1. nyu.edu/classes/bello/FMT_files/2_hearing.pdf "Hearing" by Juan P Bello
  2. "Why Can Some People Wiggle Their Ears?". Live Science . 30 March 2012.
  3. Liugan, Mikee; Zhang, Ming; Cakmak, Yusuf Ozgur (2018). "Neuroprosthetics for Auricular Muscles: Neural Networks and Clinical Aspects". Frontiers in Neurology. 8: 752. doi: 10.3389/fneur.2017.00752 . ISSN   1664-2295. PMC   5775970 . PMID   29387041.
  4. Chon, Brian H.; Blandford, Alex D.; Hwang, Catherine J.; Petkovsek, Daniel; Zheng, Andrew; Zhao, Carrie; Cao, Jessica; Grissom, Nick; Perry, Julian D. (February 2021). "Dimensions, Function and Applications of the Auricular Muscle in Facial Plastic Surgery". Aesthetic Plastic Surgery. 45 (1): 309–314. doi:10.1007/s00266-020-02045-x. ISSN   1432-5241. PMID   33258010. S2CID   227236615.
  5. Strauss, Daniel J; Corona-Strauss, Farah I; Schroeer, Andreas; Flotho, Philipp; Hannemann, Ronny; Hackley, Steven A (2020-07-03). Groh, Jennifer M; Shinn-Cunningham, Barbara G; Verhulst, Sarah; Shera, Christopher; Corneil, Brian D (eds.). "Vestigial auriculomotor activity indicates the direction of auditory attention in humans". eLife. 9: e54536. doi: 10.7554/eLife.54536 . ISSN   2050-084X. PMC   7334025 . PMID   32618268.
  6. 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.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. Богомильский, Чистякова 2002, pp. 68–69.
  8. Богомильский, Чистякова 2002, pp. 65–66.
  9. 1 2 3 Пальчун, Крюков 2001, p. 489.
  10. СЭС 1986, p. 89.
  11. СЭС 1986, p. 68.
  12. Богомильский, Чистякова 2002, pp. 66–67.
  13. Богомильский, Чистякова 2002, p. 67.
  14. Богомильский, Чистякова 2002, pp. 67–68.
  15. Асанов и др. 2003, pp. 198–199.
  16. Асанов и др. 2003, p. 198.
  17. 1 2 Богомильский, Чистякова 2002, p. 65.

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