External acoustic meatus

External acoustic meatus

Infobox Anatomy
Name =External acoustic meatus
Latin = meatus acusticus externus
GraySubject = 229
GrayPage = 1036


Caption = Anatomy of the human ear.


Caption2 =
Precursor = groove (cleft) of the first branchial arch. [EmbryologyUNC|hednk|022]
System =
Artery = anterior auricular branches
Vein =
Nerve =
Lymph =
MeshName =
MeshNumber =
DorlandsPre = m_06
DorlandsSuf = 12518132

The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the middle ear. The human ear canal extends from the pinna to the eardrum and is about 26 mm in length and 7 mm in diameter.

Structure

The human ear canal is divided into two parts. The cartilaginous part forms the outer third of the canal and contains the cartilage and the continuation of the cartilage framework of pinna. The Bony part forms the inner two thirds. The canal is approximately 26 mm long and 7 mm in diameter. Size and shape of the canal vary among individuals. This is an important factor to consider when fitting hearing protectors.

Disorders

The ear canal, because of its relative exposure to the outside world, is a common victim of diseases and other disorders. Some disorders include:
* Otitis externa (swimmer's ear), bacteria-caused inflammation of the ear canal
* Contact dermatitis of the ear canal
* Ear fungus
* Ear myiasis, an extremely rare infestation of maggots
* Bone exposure, caused by the wearing away of skin in the canal
*Granuloma, a scar usually caused by tympanostomy tubes
*Stenosis, a gradual closing of the canal
*Foreign body in ear
*Ear mites in animals.

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, fungi, and insects. Excess or impacted cerumen can press against the eardrum and/or occlude the external auditory canal and impair hearing.

References


=Additional

External links

* [http://www.nchpdp.med.va.gov/MonthlyPreventionTopics/2004_08/HowYourEarWorks.doc Veterans Health Administration web site]
* [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]
* [http://www.bris.ac.uk/Depts/ENT/otoscopy_tutorial.htm Otoscopy Tutorial w/ Images]
*


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Look at other dictionaries:

  • external acoustic meatus — noun : external auditory meatus …   Useful english dictionary

  • Acoustic meatus — can refer to: * internal acoustic meatus (or internal auditory meatus) * external acoustic meatus (or ear canal) …   Wikipedia

  • nerve of external acoustic meatus — nervus meatus acustici externi …   Medical dictionary

  • acoustic meatus — noun either of the passages in the outer ear from the auricle to the tympanic membrane • Syn: ↑auditory meatus, ↑ear canal, ↑auditory canal, ↑external auditory canal • Hypernyms: ↑meatus • Part Holonyms: ↑ …   Useful english dictionary

  • external auditory canal — n the auditory canal leading from the opening of the external ear to the eardrum called also external acoustic meatus, external auditory meatus * * * meatus acusticus externus …   Medical dictionary

  • meatus acusticus externus cartilagineus — [TA] cartilaginous external acoustic meatus: the cartilaginous part of the external acoustic meatus, found lateral to the bony part …   Medical dictionary

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  • meatus acusticus externus — [TA] external acoustic meatus: the passage of the external ear leading to the tympanic membrane, divided into an outer cartilaginous meatus and an inner bony meatus. Called also external auditory m. or canal and m. auditorius externus …   Medical dictionary

  • External ear — There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The external ear looks complicated but it is functionally the simplest part of the ear. It consists of the pinna or auricle (the visible projecting …   Medical dictionary

  • external auditory canal — ▪ anatomy also called  External Auditory Meatus, or External Acoustic Meatus,    passageway that leads from the outside of the head to the tympanic membrane, or eardrum (ear, human) membrane, of each ear. The structure of the external auditory… …   Universalium

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