View source for Eardrum

{{Short description|Membrane separating the external ear from the middle ear}}
{{Other uses}}
{{distinguish|text=the secondary tympanic membrane of the [[round window]]}}
{{Infobox anatomy
| Name        = Eardrum
| Latin       = membrana tympanica; myringa
| Image       = Blausen 0328 EarAnatomy.png
| Caption     =
| Width       =
| Image2      = View-normal-tympanic-membrane.png
| Caption2    = Right eardrum as seen through a speculum
| Precursor   =
| System      =
| Artery     =
| Vein        =
| Nerve       =
| Lymph       =
}}
{{ear series|expanded=Middle}}
In the [[anatomy]] of humans and various other [[tetrapod]]s, the '''eardrum''', also called the '''tympanic membrane''' or '''myringa''', is a thin, cone-shaped [[biological membrane|membrane]] that separates the [[external ear]] from the [[middle ear]]. Its function is to transmit changes in [[pressure]] of [[sound]] from the air to the [[ossicles]] inside the middle ear, and thence to the [[oval window]] in the fluid-filled [[cochlea]]. The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid.<ref>{{Cite journal |last=Hilal |first=Fathi |last2=Liaw |first2=Jeffrey |last3=Cousins |first3=Joseph P. |last4=Rivera |first4=Arnaldo L. |last5=Nada |first5=Ayman |date=2023-04-01 |title=Autoincudotomy as an uncommon etiology of conductive hearing loss: Case report and review of literature |url= |journal=Radiology Case Reports |language=en |volume=18 |issue=4 |pages=1461–1465 |doi=10.1016/j.radcr.2022.10.097 |issn=1930-0433 |pmc=9925837 |pmid=36798057}}</ref> The [[malleus]] bone bridges the gap between the eardrum and the other ossicles.<ref>{{cite book|editor1-last=Purves|editor1-first=D|editor2-last=Augustine|editor2-first=G|editor3-last=Fitzpatrick|editor3-first=D|editor4-last=Hall|editor4-first=W|editor5-last=LaMantia|editor5-first=A|editor6-last=White|editor6-first=L|title=Neuroscience |date=2012|publisher=Sinauer|location=Sunderland|isbn=9780878936953|display-editors=etal}}</ref>

Rupture or [[perforation of the eardrum]] can lead to [[conductive hearing loss]]. Collapse or [[tympanic membrane retraction|retraction]] of the eardrum can cause conductive hearing loss or [[cholesteatoma]].

==Structure==

===Orientation and relations===
The tympanic membrane is oriented obliquely in the [[anatomical terms of location|anteroposterior]], mediolateral, and superoinferior planes. Consequently, its superoposterior end lies lateral to its anteroinferior end.{{citation needed|date=July 2018}}

Anatomically, it relates superiorly to the [[middle cranial fossa]], posteriorly to the [[ossicle]]s and [[facial nerve]], inferiorly to the [[parotid gland]], and anteriorly to the [[temporomandibular joint]].{{citation needed|date=July 2018}}

===Regions===

The eardrum is divided into two general regions: the [[pars flaccida of tympanic membrane|pars flaccida]] and the [[pars tensa of tympanic membrane|pars tensa]].<ref>{{cite journal |last1=Gilberto |first1=Nelson |last2=Santos |first2=Ricardo |last3=Sousa |first3=Pedro |last4=O’Neill |first4=Assunção |last5=Escada |first5=Pedro |last6=Pais |first6=Diogo |title=''Pars tensa'' and tympanicomalleal joint: proposal for a new anatomic classification |journal=European Archives of Oto-Rhino-Laryngology |date=August 2019 |volume=276 |issue=8 |pages=2141–2148 |doi=10.1007/s00405-019-05434-4|pmid=31004197 |s2cid=123959777 }}</ref> The relatively fragile pars flaccida lies above the lateral [[process (anatomy)|process]] of the [[malleus]] between the [[Notch of Rivinus]] and the anterior and posterior malleal folds. Consisting of two layers and appearing slightly pinkish in hue, it is associated with{{vague|date=July 2018}} [[Eustachian tube]] dysfunction and [[cholesteatoma]]s.<ref>{{cite journal |last1=Jain |first1=Shraddha |title=Role of Eustachian Dysfunction and Primary Sclerotic Mastoid Pneumatisation Pattern in Aetiology of Squamous Chronic Otitis Media: A Correlative Study |journal=Indian Journal of Otolaryngology and Head and Neck Surgery |year=2019 |volume=71 |issue=Suppl 2 |pages=1190–1196 |doi=10.1007/s12070-018-1259-x |pmid=31750149 |pmc=6841851 }}</ref>

The larger pars tensa consists of three layers: [[skin]], [[fibrous tissue]], and [[mucosa]]. Its thick periphery forms a [[fibrocartilage|fibrocartilaginous ring]] called the [[annulus tympanicus]] or Gerlach's ligament.<ref>{{Cite book|url=https://books.google.com/books?id=M8WgDwAAQBAJ&q=gerlach+ligament&pg=PA24|title=Comprehensive and Clinical Anatomy of the Middle Ear|last1=Mansour|first1=Salah|last2=Magnan|first2=Jacques|last3=Ahmad|first3=Hassan Haidar|last4=Nicolas|first4=Karen|last5=Louryan|first5=Stéphane|date=2019|publisher=Springer|isbn=9783030153632|language=en}}</ref> while the central [[umbo of the tympanic membrane|umbo]] tents inward at the level of the tip of malleus. The middle fibrous layer, containing radial, circular, and parabolic fibers, encloses the handle of malleus. Though comparatively robust, the pars tensa is the region more commonly associated with{{vague|date=July 2018}} perforations.<ref>{{cite journal | title=Endoscopic Anatomy of the Middle Ear |vauthors=Marchioni D, Molteni G, Presutti L | date=February 2011 | journal=Indian J Otolaryngol Head Neck Surg | volume=63 | issue = 2 | pages=101–13 | doi=10.1007/s12070-011-0159-0 | pmc=3102170 | pmid=22468244}}</ref>

===Umbo===
The manubrium (Latin for "handle") of the [[malleus]] is firmly attached to the medial surface of the membrane as far as its center, drawing it toward the [[tympanic cavity]]. The lateral surface of the membrane is thus concave. The most depressed aspect of this concavity is termed the umbo (Latin for "[[shield boss]]").<ref>Gray's Anatomy (1918)</ref>

===Nerve supply===
Sensation of the outer surface of the tympanic membrane is supplied mainly by the [[auriculotemporal nerve]], a branch of the [[mandibular nerve]] ([[cranial nerve]] [[trigeminal nerve|V<sub>3</sub>]]), with contributions from the [[auricular branch of the vagus nerve]] ([[vagus nerve|cranial nerve X]]), the [[facial nerve]] (cranial nerve VII), and possibly the [[glossopharyngeal nerve]] (cranial nerve IX). The inner surface of the tympanic membrane is innervated by the glossopharyngeal nerve.<ref>Drake, Richard L., A. Wade Vogl, and Adam Mitchell. Gray's Anatomy For Students. 3rd ed. Philadelphia: Churchill Livingstone, 2015. Print. pg. 969</ref>

==Clinical significance==

===Examination===
When the eardrum is illuminated during a [[medical examination]], a [[Cone of Light|cone of light]] radiates from the tip of the malleus to the periphery in the anteroinferior quadrant, this is what is known clinically as 5 o'clock.{{citation needed|date=July 2018}}

===Rupture===
Unintentional [[perforated eardrum|perforation]] (rupture) has been described in [[blast injuries]]<ref>{{cite journal | title=Tympanic membrane perforation and hearing loss from blast overpressure in Operation Enduring Freedom and Operation Iraqi Freedom wounded |vauthors=Ritenour AE, Wickley A, Retinue JS, Kriete BR, Blackbourne LH, Holcomb JB, Wade CE | date=February 2008 | journal=J Trauma | volume=64|issue=2 Suppl|doi=10.1097/ta.0b013e318160773e  |pmid=18376162 | pages=S174-8 }}</ref> and [[air travel]], typically in patients experiencing [[upper respiratory infection|upper respiratory]] [[nasal congestion|congestion]] or general [[Eustachian tube dysfunction]] that prevents equalization of pressure in the middle ear.<ref>{{cite journal | title=Otic barotrauma from air travel |vauthors=Mirza S, Richardson H | date=May 2005 | journal=J Laryngol Otol | volume=119 | pages=366–70 | pmid=15949100 | doi=10.1258/0022215053945723 | issue=5|s2cid=45256115 }}</ref> It is also known to occur in [[swimming]], [[Underwater diving|diving]] (including [[scuba diving]]),<ref>{{cite journal | title=Tympanometric evaluation of middle ear barotrauma during recreational scuba diving |author1=Green SM |author2=Rothrock SG |author3=Green EA= | date=October 1993 | journal=Int J Sports Med | volume=14 | pages=411–5 | pmid=8244609 | doi=10.1055/s-2007-1021201 | issue=7}}</ref> and [[martial arts]].<ref>{{cite journal | title=Traumatic tympanic membrane rupture in a mixed martial arts competition |vauthors=Fields JD, McKeag DB, Turner JL | date=February 2008 | journal=Current Sports Med Rep | volume=7 | pages=10–11 | pmid=18296937| doi=10.1097/01.CSMR.0000308672.53182.3b | issue=1|s2cid=205388185 | doi-access=free }}</ref>

Patients with tympanic membrane rupture may experience bleeding, [[tinnitus]], [[hearing loss]], or disequilibrium ([[vertigo]]). However, they rarely require medical intervention, as between 80 and 95 percent of ruptures recover completely within two to four weeks.<ref>{{cite journal | title=Spontaneous healing of traumatic tympanic membrane perforations in man: a century of experience | author=Kristensen S | date=December 1992 | journal=J Laryngol Otol | volume=106 | pages=1037–50 | pmid=1487657 | issue=12 | doi=10.1017/s0022215100121723| s2cid=21899785 }}</ref><ref>{{cite journal | title=Acute traumatic tympanic membrane perforations. Cover or observe? |vauthors=Lindeman P, Edström S, Granström G, Jacobsson S, von Sydow C, Westin T, Aberg B | date=December 1987 | journal=Arch Otolaryngol Head Neck Surg | volume=113 | pages=1285–7 | pmid=3675893 | issue=12 | doi=10.1001/archotol.1987.01860120031002}}</ref><ref name=Garth>{{cite journal | title=Blast injury of the ear: an overview and guide to management | author=Garth RJ | date=July 1995 | journal=Injury | volume=26 | issue = 6 | pages=363–6 | doi=10.1016/0020-1383(95)00042-8| pmid=7558254 }}</ref> The prognosis becomes more guarded as the force of injury increases.<ref name=Garth/>

===Surgical puncture for treatment of middle ear infections===
In some cases, the pressure of fluid in an infected middle ear is great enough to cause the eardrum to rupture naturally. Usually, this consists of a small hole (perforation), from which fluid can drain out of the middle ear. If this does not occur naturally, a [[myringotomy]] (tympanotomy, tympanostomy) can be performed. A myringotomy is a [[surgery|surgical]] procedure in which a tiny incision is created in the eardrum to relieve pressure caused by excessive buildup of fluid, or to drain [[pus]] from the [[middle ear]]. The fluid or pus comes from a middle ear infection ([[otitis media]]), which is a common problem in children. A [[tympanostomy tube]] is inserted into the eardrum to keep the middle ear aerated for a prolonged time and to prevent reaccumulation of fluid.  Without the insertion of a tube, the incision usually heals spontaneously in two to three weeks.  Depending on the type, the tube is either naturally extruded in 6 to 12 months or removed during a minor procedure.<ref name=Tube />

Those requiring myringotomy usually have an obstructed or dysfunctional [[Eustachian tube]] that is unable to perform drainage or ventilation in its usual fashion.  Before the invention of antibiotics, myringotomy without tube placement was also used as a major treatment of severe acute otitis media.<ref name=Tube>{{cite journal | title=To tube or not to tube: indications for myringotomy with tube placement |vauthors=Smith N, Greinwald JR | year=2011 | journal=Current Opinion in Otolaryngology & Head and Neck Surgery | volume=19 | pages=363–366|pmid=21804383 | doi=10.1097/MOO.0b013e3283499fa8 | issue=5|s2cid=3027628 }}</ref>

==Society and culture==
The [[Bajau]] people of the [[Pacific]] intentionally rupture their eardrums at an early age to facilitate diving and hunting at sea. Many older Bajau therefore have difficulties hearing.<ref>{{cite news |last=Langenheim |first=Johnny |date=18 September 2010 |title= The last of the sea nomads|url=https://www.theguardian.com/environment/2010/sep/18/last-sea-nomads |newspaper=[[The Guardian]] |access-date=15 February 2016 }}</ref>

==See also==
* [[Middle ear]]
* [[Valsalva maneuver]] to equalize pressure across the eardrum

==Additional images==
<gallery>
File:Anatomy of the Human Ear en.svg|Anatomy of the human right ear.{{Anatomy of the human ear - color legend}}
File:Gray907.png|External and middle ear, right side, opened from the front (coronal section)
File:Gray908.png|Horizontal section through left ear; upper half of section
File:Gray912.png|The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above
File:Gray915.png|Auditory tube, laid open by a cut in its long axis
File:Gray919.png|Chain of ossicles and their ligaments, seen from the front in a vertical, transverse section of the tympanum (tympanic cavity)
File:Gray909.png|Right eardrum as seen through a speculum
File:Normal Left Tympanic Membrane.jpg|This is a normal left eardrum.
File:Tympanic membrane viewed by otoscope.png|Tympanic membrane viewed by otoscope
File:Traumatic Perforation of the Tympanic Membrane.jpg|The oval perforation in this left tympanic membrane was the result of a slap on the ear
File:Subtotal Perforation of the right tympanic membrane.tif|A subtotal perforation of the right tympanic membrane resulting from a previous severe otitis media
File:TM RIGHT NORMAL.jpg|A normal human right tympanic membrane (eardrum)
File:Frog on leaf with eardrum.jpg|Frog on leaf showing [[tympanum (anatomy)|tympanum]]
</gallery>

==References==
{{Gray's}}
{{Reflist|30em}}

==External links==
{{Commons category}}
* [http://hyperphysics.phy-astr.gsu.edu/hbase/sound/ear.html Diagram at Georgia State University]
* [https://web.archive.org/web/20130504141252/http://www.drtbalu.com/tm_memb.html drtbalu's otolaryngology online]

{{Auditory and vestibular anatomy}}
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[[Category:Auditory system]]
[[Category:Ear]]
[[Category:Otorhinolaryngology]]
[[Category:Otology]]
[[Category:Human anatomy]]