- External acoustic meatus
Name =External acoustic meatus
Latin = meatus acusticus externus
GraySubject = 229
GrayPage = 1036
Caption = Anatomy of the human ear.
Precursor = groove (cleft) of the
first branchial arch. [EmbryologyUNC|hednk|022]
Artery = anterior auricular branches
DorlandsPre = m_06
DorlandsSuf = 12518132
The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the
outer earto the middle ear. The human ear canal extends from the pinna to the eardrumand is about 26 mm in length and 7 mm in diameter.
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
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 dermatitisof the ear canal
* Ear fungus
myiasis, an extremely rare infestation of maggots
* Bone exposure, caused by the wearing away of skin in the canal
Granuloma, a scarusually caused by tympanostomy tubes
Stenosis, a gradual closing of the canal
*Foreign body in ear
Ear mites in animals.
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.
* [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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