Editing Eardrum (section)

==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>