The ear canal, also known as the External Auditory Meatus, part of the ear, is a tube running from the outer ear to the middle ear. The ear canal extends from the pinna to the eardrum and is about 26 millimeters (mm) in length and 7 mm in diameter. Size and shape vary among individuals. This is an important factor to consider when fitting hearing protectors. The ear canal protects the eardrum and acts as a resonator, providing about 10 decibels (dB) of gain to the eardrum at around 3,300 Hertz (Hz). The net effect of the head, pinna, and ear canal is that sounds in the 2,000 to 4,000 Hz region are amplified by 10 to 15 dB. Sensitivity to sounds is greatest in this frequency region and noises in this range are the most hazardous to hearing. The outer foundation of the ear canal is cartilage covered with skin that contains hairs and glands that secrete wax. The hairs and wax (cerumen) help prevent foreign bodies, such as insects or dust, from entering the ear canal. human ear anatomy I made this myself Iain 05:39 29 Jun 2003 (UTC) version without labels File links The following pages link to this file: Ear Categories: GFDL images ... human ear anatomy I made this myself Iain 05:39 29 Jun 2003 (UTC) version without labels File links The following pages link to this file: Ear Categories: GFDL images ... A left human ear. ... For an alternative meaning, see ear (botany). ... The pinna is the visible part of the ear that resides outside of the head. ... The tympanum or tympanic membrane, colloquially known as eardrum, is a thin membrane that separates the outer ear from the middle ear. ... The decibel is a dimensionless unit (like percent) that is a measure of ratios on a logarithmic scale. ... The hertz (symbol Hz) is the SI unit of frequency. ... Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... Cartilage is a type of dense connective tissue. ... Model of the layers of human skin In zootomy and dermatology, skin is an organ of the integumentary system; which is composed of a layer of tissues that protect underlying muscles and organs. ... Cerumen, commonly known as earwax, is a yellowish, waxy substance secreted in the ear canal of humans and many other mammals. ...
On the cranial surface of the pinna elevations correspond to the concha and to the fossae a, Helix.
The externalauditorymeatus, tympanum and Eustachian tube are remains of the hyomandibular cleft, the membrana tympani being a remnant of the cleft membrane and therefore lined by ectoderm outside and entoderm inside.
The chief diseases of the externalauditory canal are as follows: - impacted cerumen (or wax), circumscribed (or furuncular) inflammation, diffuse inflammation, strictures due to inflammatory affections, bony growths, fungi (otomycosis), malignant disease, caries and necrosis, and foreign bodies.
Between the posterior wall of the external acoustic meatus and the posterior root of the zygomatic process is the area called the suprameatal triangle (Macewen), or mastoid fossa, through which an instrument may be pushed into the tympanic antrum.
It transmits the facial and acoustic nerves and the internal auditory branch of the basilar artery.
The descent of the foramen is necessarily accompanied by a corresponding lengthening of the facial canal.
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