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Encyclopedia > Eardrum

Eardrum
Anatomy of the human ear.
Right tympanic membrane as seen through a speculum.
Latin membrana tympani
Gray's subject #230 1039
MeSH Tympanic+Membrane

The tympanic membrane, colloquially known as the eardrum, 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. 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 ... Image File history File links No higher resolution available. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... A biological membrane or biomembrane is an enclosing or separating tissue which acts as a barrier within or around a cell. ... A left human ear. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ... Sound is a disturbance of mechanical energy that propagates through matter as a longitudinal wave. ... The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ... The malleus is hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. ...


Rupture or perforation of the eardrum can lead to conductive hearing loss. Rupture or perforation (hole) of the eardrum can occur in infection, trauma (e. ... Conductive hearing loss is a failure in the efficient conduction of sound waves through the outer ear, typanic membrane (eardrum) or middle ears (ossicles). ...

Contents

Development

The tympanic membrane forms from the joining of the expanding first pharyngeal pouch and groove. Around day 30 of gestation, the endoderm-lined first pharyngeal pouch 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. A pharyngeal pouch is a pulsion diverticulum of the pharyngeal mucosa through Killians dehiscence. ... Schematic of developing fetus with first, second and third arches labeled. ... Gestation is the carrying of an embryo or fetus inside a female viviparous animal. ... The endoderm, sometimes refered to as entoderm, is one of the three germ layers of the developing embryo, the other two being the ectoderm and the mesoderm. ... The tympanic cavity is a small cavity surrounding the bones of the inner ear. ... The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ... Anatomy of the human ear. ... Lateral plate mesoderm (or hypomere) is a type of mesoderm that is found at the periphery of the embryo. ... Organs derived from each germ layer. ... The ectoderm is outermost of the three germ layers of the developing embryo, the other two being the mesoderm and the endoderm. ... The mesoderm is one of the three germ layers in the early developing embryo, the other two layers being the ectoderm and the endoderm. ... The endoderm, sometimes refered to as entoderm, is one of the three germ layers of the developing embryo, the other two being the ectoderm and the mesoderm. ...


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." 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. Otoscope - Image of an otoscope (center) An Otoscope is a medical device which is used to look into the ears. ... Court Jester Umbo Scrubbelnuts Umbo is a character in the popular fantasy role-playing game, EverQuest. ... The chorda tympani are nerves of special sensation given off the facial nerve (VII) inside the skull. ...


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External links


  Results from FactBites:
 
Perforated Eardrum (732 words)
A perforated eardrum is a hole or rupture in the eardrum, a thin membrane which separates the ear canal and the middle ear.
A perforated eardrum is often accompanied by decreased hearing and occasional discharge.
The causes of perforated eardrum are usually from trauma or infection.
  More results at FactBites »

 

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