AskDefine | Define eardrum

Dictionary Definition

eardrum n : the membrane in the ear that vibrates to sound [syn: tympanum, tympanic membrane, myringa]

User Contributed Dictionary

English

Noun

  1. A thin membrane that separates the outer ear from the middle ear and transmits sound from the air to the malleus.

Translations

  • Capeverdean Crioulo:
Badiu/ALUPEC or ALUPEK: tinpanu or timpan'
São Vicente Crioulo: timpan'
Cyrillic: бубна опна
Latin/Roman: ubna olna

Extensive Definition

The tympanic membrane (also tympanum or myrinx), is a thin membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles.

Development

The eardrum forms from the joining of the expanding first pharyngeal pouch and groove. Around day 30 of gestation, the endoderm-lined first expands to form the tympanic cavity, which subsequently envelops the inner ear ossicles. Simultaneously, the first pharyngeal groove, which is lined with ectoderm, expands to form the developing external auditory meatus. Separated by a thin layer of splanchnic mesoderm, the tympanic cavity and external auditory meatus join to form the tympanic membrane. As a result, the tympanic membrane is one of very few adult structures that is derived from all three germ layers. The skin that covers the outer surface of the tympanic membrane is derived from ectoderm, the fibrous tissue that forms the actual membrane is derived from mesoderm, and the mucus membrane that lines the inner surface of the membrane is derived from endoderm.

Clinical Aspects

When examining the tympanic membrane with an otoscope, a bright cone of light is seen in the anterior-inferior part of the membrane. This light is known as the "cone of light" or "light reflex". The tympanic membrane is separated into four quadrants, with the center of the four quadrants being the umbo. Nerves, specifically the chorda tympani nerve, and arteries pass through the layers of the superior portion of the membrane. Thus, when the tympanic membrane needs to be incised for medical procedures, ENT surgeons will always cut through the inferior and posterior part of the membrane to avoid the vasculature, nerves, and bones associated with the membrane. The human body only contains 1 eardrum

Additional images

eardrum in German: Trommelfell
eardrum in Estonian: Trummikile
eardrum in Spanish: Tímpano
eardrum in French: Tympan (anatomie)
eardrum in Galician: Tímpano
eardrum in Indonesian: Gendang telinga
eardrum in Italian: Timpano (anatomia)
eardrum in Hebrew: עור התוף
eardrum in Croatian: Bubnjić
eardrum in Latin: Membrana tympani
eardrum in Lithuanian: Būgnelis
eardrum in Dutch: Trommelvlies
eardrum in Japanese: 鼓膜
eardrum in Norwegian: Trommehinne
eardrum in Norwegian Nynorsk: Trommehinne
eardrum in Polish: Błona bębenkowa
eardrum in Portuguese: Membrana timpânica
eardrum in Slovak: Bubienok (cicavce)
eardrum in Serbian: Бубна опна
eardrum in Sundanese: Kendang ceuli
eardrum in Swedish: Trumhinna
eardrum in Finnish: Tärykalvo
eardrum in Telugu: కర్ణభేరి
eardrum in Ukrainian: Барабанна перетинка

Synonyms, Antonyms and Related Words

Eustachian tube, allantoic membrane, amnion, amniotic sac, anvil, arachnoid membrane, auditory apparatus, auditory canal, auditory meatus, auditory nerve, auditory ossicles, auditory tube, auricle, basement membrane, basilar membrane, bony labyrinth, cauliflower ear, cochlea, conch, concha, conjuctiva, drumhead, ear, ear lobe, endolymph, external ear, hammer, hymen, incus, inner ear, lobe, lobule, lug, maidenhead, malleus, mastoid process, membrana serosa, membrana tympana, membrane, meninges, meninx, middle ear, neurilemma, organ of Corti, outer ear, oval window, pellicle, pericardium, perilymph, perineurium, pinna, pleura, round window, secondary eardrum, semicircular canals, serosa, shell, stapes, stirrup, tympanic cavity, tympanic membrane, tympanum, velum, vestibule
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