# Ear canal

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{{Short description|Tube running from the outer ear to the middle ear}}
{{Infobox anatomy
| Name        = Ear canal
| Latin       = meatus acusticus externus
| Image       = Ear-anatomy-text-small-en.svg
| Caption     = Anatomy of the human ear.
| Image2      =
| Caption2    =
| Precursor   = Groove (cleft) of the [first branchial arch](/source/first_branchial_arch)<ref>{{EmbryologyUNC|hednk|022}}</ref>
| System      =
| Artery      = Anterior part: [superficial temporal artery](/source/Anterior_auricular_branches_of_superficial_temporal_artery)<br />posterior part: [posterior auricular artery](/source/posterior_auricular_artery)
| Vein        = [Superficial temporal vein](/source/Superficial_temporal_vein)s, [external jugular vein](/source/external_jugular_vein), [pterygoid plexus](/source/pterygoid_plexus)
| Nerve       = [Auriculotemporal nerve](/source/Auriculotemporal_nerve), [great auricular nerve](/source/great_auricular_nerve), [auricular branch of vagus nerve](/source/auricular_branch_of_vagus_nerve)
| Lymph       = [Superficial cervical lymph nodes](/source/Superficial_cervical_lymph_nodes), [deep cervical lymph nodes](/source/deep_cervical_lymph_nodes)
}}

The '''ear canal''' ('''external acoustic meatus''', '''external auditory meatus''', '''EAM''') is a pathway running from the [outer ear](/source/outer_ear) to the [middle ear](/source/middle_ear). The adult human ear canal extends from the [auricle](/source/Auricle_(anatomy)) to the [eardrum](/source/eardrum) and is about {{convert|25|mm|0}} in length and {{convert|7|mm|1}} in diameter.

== Structure==
The human ear canal is divided into two parts. The elastic cartilage part forms the outer third of the canal; its anterior and lower wall are cartilaginous, whereas its superior and back wall are fibrous. The cartilage is the continuation of the cartilage framework of auricle. The cartilaginous portion of the ear canal contains small hairs and specialized sweat glands, called [ceruminous gland](/source/ceruminous_gland)s, which produce cerumen ([ear wax](/source/Earwax)). The bony part forms the inner two thirds. The bony part is much shorter in children and is only a ring (''annulus tympanicus'') in the newborn. The layer of epithelium encompassing the bony portion of the ear canal is much thinner and therefore, more sensitive in comparison to the cartilaginous portion.

Size and shape of the canal vary among individuals. The canal is approximately {{convert|25|mm|0}} long and {{convert|7|mm}} in diameter.<ref>Faddis, B. T. (2008). "Structural and functional anatomy of the outer and middle ear". In W. Clark & K. Ohlemiller (Eds.), ''Anatomy and physiology of hearing for audiologists'' (pp. 93–108). Thomson Delmar Learning.</ref> It has a sigmoid form and runs from behind and above downward and forward. On the cross-section, it is of oval shape. These are important factors to consider when fitting [earplug](/source/earplug)s.

==Disorders==
Due to its relative exposure to the outside world, the ear canal is susceptible to diseases and other disorders. Some disorders include:
* [Atresia](/source/Atresia) of the ear canal
*Cerumen impaction
* Bone exposure, caused by the wearing away of skin in the canal
*Auditory canal [osteoma](/source/osteoma) (bony outgrowths of the temporal bone)
*[Cholesteatoma](/source/Cholesteatoma)
* [Contact dermatitis](/source/Contact_dermatitis) of the ear canal
* Fungal infection ([otomycosis](/source/otomycosis))
*[Ear mite](/source/Ear_mite)s in animals
* Ear [myiasis](/source/myiasis), an extremely rare infestation of maggots
*Foreign body in ear
*[Granuloma](/source/Granuloma), a [scar](/source/scar) usually caused by [tympanostomy tube](/source/tympanostomy_tube)s
* [Otitis externa](/source/Otitis_externa) (swimmer's ear), bacteria-caused inflammation of the ear canal
*[Stenosis](/source/Stenosis), a gradual closing of the canal

==Earwax==
{{Main|Earwax}}
Earwax, also known as cerumen, is a yellowish, waxy substance secreted in the ear canals. It plays an important role in the human ear canal, assisting in cleaning and lubrication, and also provides some protection from [bacteria](/source/bacterium), [fungi](/source/fungus), and [insect](/source/insect)s. Excess or impacted cerumen can press against the eardrum and/or occlude the external auditory canal and impair hearing, causing [conductive hearing loss](/source/conductive_hearing_loss). If left untreated, cerumen impaction can also increase the risk of developing an infection within the ear canal.

==Additional images==
<gallery>
 File:Gray187.png|Base of skull. Inferior surface.
 File:Gray189.png|Left infratemporal fossa.
 File:Gray907.png|External and middle ear, opened from the front. Right side.
 File:Gray908.png|Horizontal section through left ear; upper half of section.
 File:Slide1CAC.JPG|Lateral head anatomy detail. Facial nerve dissection.
</gallery>

== See also ==
* [List of specialized glands within the human integumentary system](/source/List_of_specialized_glands_within_the_human_integumentary_system)

==References==
{{Reflist}}

== External links ==
*[https://web.archive.org/web/20051022085858/http://www.nchpdp.med.va.gov/MonthlyPreventionTopics/2004_08/HowYourEarWorks.doc Veterans Health Administration web site]
*[https://web.archive.org/web/20060910163204/http://www.osha.gov/dts/osta/otm/noise/health_effects/physiology.html OSHA web site]
*[http://www.entusa.com/external_ear_canal.htm Continuing Medical Education Ear Photographs] {{Webarchive|url=https://web.archive.org/web/20210424195528/http://www.entusa.com/external_ear_canal.htm |date=2021-04-24 }}
*[https://www.entbristol.co.uk/gp-education Otoscopy Tutorial w/ Images]
* {{cite web|url=http://www.tk.de/rochelexikon/pics/s34257.000-1.html|title=Anatomy diagram: 34257.000-1|work=Roche Lexicon - illustrated navigator|publisher=Elsevier|archive-url=https://web.archive.org/web/20120722052131/http://www.tk.de/rochelexikon/pics/s34257.000-1.html|archive-date=2012-07-22|url-status=dead}}

{{Auditory system}}
{{Authority control}}

Category:Auditory system
Category:Ear
Category:Otology
Category:Audiology

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Adapted from the Wikipedia article [Ear canal](https://en.wikipedia.org/wiki/Ear_canal) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Ear_canal?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.