ear canal

External acoustic meatus
Anatomy of the human ear.
Latin	meatus acusticus externus
Gray's	subject #229 1036
Artery	anterior auricular branches
Precursor	groove (cleft) of the first branchial arch.[1]

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

1. ^ hednk-022 — Embryology at UNC

Additional images

Base of skull. Inferior surface.

Left infratemporal fossa.

External and middle ear, opened from the front. Right side.

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