Ear canal

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Main article: External ear

The ear canal, or external auditory meatus, 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 26mm in length and 7 mm in diameter.

Contents 1 Description and acoustic characteristics 2 Size and shape 3 Additional images 4 References

[edit] Description and acoustic characteristics

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.

The ear canal protects the eardrum and acts as a resonator, providing about 10 dB of gain to the eardrum at around 3,300 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 between 10 and 15 dB. Sensitivity to sounds is greatest in this frequency region and therefore excessive noise in this range is the most likely to cause hearing damage.

The external auditory meatus is formed from the groove (cleft) of the first branchial arch.

[edit] Size and shape

The ear canal is approximately 26mm long and 7mm in diameter. Size and shape of the canal vary among individuals. This is an important factor to consider when fitting hearing protectors.

[edit] Additional images

Left infratemporal fossa.

[edit] References

• Veterans Health Administration web site
• OSHA web site
• Continuing Medical Education Ear Photographs

v·d·e Sensory system: Auditory and Vestibular systems
Outer ear	pinna (Helix, Antihelix, Tragus, Antitragus, Earlobe) • Ear canal
Middle ear	Eardrum (Umbo) • Ossicles (Malleus, Incus & Stapes) • Stapedius • Tensor tympani • Eustachian tube (Torus tubarius)
Inner ear/Labyrinth	Bony labyrinth (Vestibule) • Membranous labyrinth Oval window • Helicotrema • Round window Cochlea: Spiral ganglion • Modiolus • Cochlear duct/scala media (Endolymph, Stria vascularis, Spiral ligament, Organ of Corti) • Scala vestibuli and Scala tympani (Perilymph) Reissner's/vestibular membrane • Basilar membrane • Tectorial membrane Organ of Corti: Hair cells • Stereocilia • Sulcus spiralis (externus, internus) • Limbus spiralis
Vestibular system	Static/translations: Utricle (Macula) - Saccule (Macula, Endolymphatic sac, Endolymphatic duct) - Kinocilium - Otolith Kinetic/rotations: Semicircular canals (Superior, Posterior, Horizontal) • Cupula • Ampullae (Crista ampullaris)
Brain (auditory)	Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Lateral lemniscus → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex

This page uses content from the English-language version of Wikipedia. The original article was at Ear canal. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.