Ear Canal Information
The ear canal (external auditory meatus, external acoustic meatus) (Latin: meatus acusticus externus) , 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 35 mm in length and 5 to 10 mm in diameter.
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Structure
The human ear canal is divided into two parts. The fibrocartilaginous 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 pinna. 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.
Size and shape of the canal vary among individuals. The canal is approximately 35 mm long and 5 to 10 mm in diameter. 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 earplugs.
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:
- Atresia of the ear canal
- 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
- Cholesteatoma
- Ear mites in animals.
Earwax
Main article: EarwaxEarwax, 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 images
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Base of skull. Inferior surface.
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Left infratemporal fossa.
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External and middle ear, opened from the front. Right side.
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Horizontal section through left ear; upper half of section.
External links
- Veterans Health Administration web site
- OSHA web site
- Continuing Medical Education Ear Photographs
- Otoscopy Tutorial w/ Images
- Roche Lexicon - illustrated navigator, at Elsevier 34257.000-1
Categories: Auditory system | Ear
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