Editing Larynx (section)

== Structure ==
[[File:Larynx.svg|thumb|The basic parts of the human larynx.]]
The triangle-shaped larynx consists largely of cartilages that are attached to one another, and to surrounding structures, by muscles or by fibrous and elastic tissue components. The larynx is lined by a [[respiratory epithelium|ciliated columnar epithelium]] except for the vocal folds. The [[laryngeal cavity|cavity of the larynx]] extends from its triangle-shaped [[laryngeal inlet|inlet]], to the [[epiglottis]], and to the circular outlet at the lower border of the [[cricoid cartilage]], where it is continuous with the lumen of the trachea. The mucous membrane lining the larynx forms two pairs of lateral folds that project inward into its cavity. The upper folds are called the [[vestibular fold]]s. They are also sometimes called the false vocal cords for the rather obvious reason that they play no part in vocalization. The [[Tuvan_throat_singing#Kargyraa|Kargyraa]] style of [[Tuvan throat singing]] makes use of these folds to sing an octave lower, and they are used in [[Overtone_singing#South_Africa|Umngqokolo]], a type of Xhosa throat singing. The lower pair of folds are known as the vocal cords, which produce sounds needed for speech and other vocalizations. The slit-like space between the left and right vocal cords, called the rima glottidis, is the narrowest part of the larynx. The vocal cords and the rima glottidis are together designated as the glottis. The laryngeal cavity above the vestibular folds is called the vestibule. The very middle portion of the cavity between the vestibular folds and the vocal cords is the ventricle of the larynx, or laryngeal ventricle. The infraglottic cavity is the open space below the glottis.

===Location===
In adult humans, the larynx is found in the [[anterior]] neck at the level of the [[cervical vertebrae]] C3–C6. It connects the inferior part of the [[pharynx]] (hypopharynx) with the [[trachea]]. The laryngeal [[skeleton]] consists of nine [[cartilage]]s: three single ([[Epiglottic cartilage|epiglottic]], [[thyroid cartilage|thyroid]] and [[Cricoid cartilage|cricoid]]) and three paired ([[Arytenoid cartilage|arytenoid]], [[corniculate cartilages|corniculate]], and [[Cuneiform cartilages|cuneiform]]).<ref name="Knipe">{{cite web | vauthors = Knipe H |title=Laryngeal cartilages | work = Radiology Reference Article | publisher = Radiopaedia.org |url=https://radiopaedia.org/articles/laryngeal-cartilages?lang=gb }}</ref> The [[hyoid bone]] is not part of the larynx, though the larynx is suspended from the hyoid. The larynx extends vertically from the tip of the [[epiglottis]] to the inferior border of the [[cricoid cartilage]]. Its interior can be divided in supraglottis, [[glottis]] and [[subglottis]].
[[File:Illu07 larynx02.jpg|thumb|upright=1.3|Vocal cords abducted and adducted]]

===Cartilages===
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| footer = Posterior view of the larynx; disarticulated cartilages (left) and intrinsic muscles (right)
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There are nine cartilages, three unpaired and three paired (3 pairs=6), that support the mammalian larynx and form its skeleton.<ref>{{cite web|vauthors=Suárez-Quintanilla J, Fernández Cabrera A, Sharma S |title=Anatomy, Head and Neck: Larynx |url=https://www.ncbi.nlm.nih.gov/books/NBK538202/ |publisher=StatPearls, National Library of Medicine, US National Institutes of Health |access-date=2 February 2025|date=4 September 2023}}</ref>

Unpaired cartilages:
* [[Thyroid cartilage]]: This forms the [[Adam's apple]] (also called the laryngeal prominence). It is usually larger in males than in females. The [[thyrohyoid membrane]] is a ligament associated with the thyroid cartilage that connects it with the hyoid bone. It supports the front portion of the larynx. 
* [[Cricoid cartilage]]: A ring of hyaline cartilage that forms the inferior wall of the larynx. It is attached to the top of the trachea. The [[median cricothyroid ligament]] connects the cricoid cartilage to the thyroid cartilage.
* [[Epiglottis]]: A large, spoon-shaped piece of elastic cartilage. During [[swallowing]], the pharynx and larynx rise. Elevation of the pharynx widens it to receive food and drink; elevation of the larynx causes the epiglottis to move down and form a lid over the glottis, closing it off.
Paired cartilages:
* [[Arytenoid cartilage]]s: Of the paired cartilages, the arytenoid cartilages are the most important because they influence the position and tension of the [[vocal cords]]. These are triangular pieces of mostly hyaline cartilage located at the posterosuperior border of the cricoid cartilage.
* [[Corniculate cartilages]]: Horn-shaped pieces of elastic cartilage located at the apex of each arytenoid cartilage.
* [[Cuneiform cartilages]]: Club-shaped pieces of elastic cartilage located anterior to the corniculate cartilages.

===Muscles===
The muscles of the larynx are divided into ''intrinsic'' and ''extrinsic'' muscles. The extrinsic muscles act on the region and pass between the larynx and parts around it but have their origin elsewhere; the intrinsic muscles are confined entirely within the larynx and have their origin and insertion there.<ref name="Saladin">{{cite book | vauthors = Saladin KS |title=Human anatomy |date=2011 |publisher=McGraw-Hill |location=New York |isbn=9780071222075 |page=241 |edition=3rd}}</ref>

The intrinsic muscles are divided into respiratory and the phonatory muscles (the muscles of [[phonation]]). The respiratory muscles move the [[vocal cord]]s apart and serve breathing. The phonatory muscles move the vocal cords together and serve the production of voice. The main respiratory muscles are the [[posterior cricoarytenoid muscle]]s. The phonatory muscles are divided into adductors ([[lateral cricoarytenoid muscle]]s, [[arytenoid muscle]]s) and tensors ([[cricothyroid muscle]]s, [[thyroarytenoid muscle]]s).

====Intrinsic====
The intrinsic laryngeal muscles are responsible for controlling sound production.
* [[Cricothyroid muscle]] lengthen and tense the vocal cords.
* [[Posterior cricoarytenoid muscle]]s abduct and externally rotate the arytenoid cartilages, resulting in abducted vocal cords.
* [[Lateral cricoarytenoid muscle]]s adduct and internally rotate the arytenoid cartilages, increase medial compression.
* [[Transverse arytenoid muscle]] adduct the arytenoid cartilages, resulting in adducted vocal cords.<ref>Collectively, the transverse and oblique arytenoids are known as the interarytenoids.</ref>
* [[Oblique arytenoid muscle]]s narrow the [[laryngeal inlet]] by constricting the distance between the arytenoid cartilages.
* [[Thyroarytenoid muscle]]s narrow the laryngeal inlet, shortening the vocal cords, and lowering voice pitch. The internal thyroarytenoid is the portion of the thyroarytenoid that vibrates to produce sound.

Notably the only muscle capable of separating the vocal cords for normal breathing is the posterior cricoarytenoid.  If this muscle is incapacitated on both sides, the inability to pull the vocal cords apart (abduct) will cause difficulty breathing. Bilateral injury to the recurrent laryngeal nerve would cause this condition.  It is also worth noting that all muscles are innervated by the recurrent laryngeal branch of the vagus except the cricothyroid muscle, which is innervated by the external laryngeal branch of the superior laryngeal nerve (a branch of the vagus).

Additionally, intrinsic laryngeal muscles present a constitutive [[Calcium buffering|Ca<sup>2+</sup>-buffering]] profile that predicts their better ability to handle calcium changes in comparison to other muscles.<ref name="Expression of calcium-buffering pro">{{cite journal | vauthors = Ferretti R, Marques MJ, Khurana TS, Santo Neto H | title = Expression of calcium-buffering proteins in rat intrinsic laryngeal muscles | journal = Physiological Reports | volume = 3 | issue = 6 | page = e12409 | date = June 2015 | pmid = 26109185 | pmc = 4510619 | doi = 10.14814/phy2.12409 }}</ref> This profile is in agreement with their function as very fast muscles with a well-developed capacity for prolonged work. Studies suggests that mechanisms involved in the prompt sequestering of Ca<sup>2+</sup> (sarcoplasmic reticulum Ca<sup>2+</sup>-reuptake proteins, plasma membrane pumps, and cytosolic Ca<sup>2+</sup>-buffering proteins) are particularly elevated in laryngeal muscles, indicating their importance for the myofiber function and protection against disease, such as [[Duchenne muscular dystrophy]].<ref name="onlinelibrary.wiley.com">{{cite journal | vauthors = Marques MJ, Ferretti R, Vomero VU, Minatel E, Neto HS | title = Intrinsic laryngeal muscles are spared from myonecrosis in the mdx mouse model of Duchenne muscular dystrophy | journal = Muscle & Nerve | volume = 35 | issue = 3 | pages = 349–353 | date = March 2007 | pmid = 17143878 | doi = 10.1002/mus.20697 | s2cid = 41968787 }}</ref> Furthermore, different levels of Orai1 in rat intrinsic laryngeal muscles and [[extraocular muscle]]s over the limb muscle suggests a role for store operated [[Calcium channel|calcium entry channels]] in those muscles' functional properties and signaling mechanisms.

====Extrinsic====
The extrinsic laryngeal muscles support and position the larynx within the mid-cervical cereal region. 
[[File:Gray386.png|thumb|Extrinsic laryngeal muscles]]
* [[Sternothyroid muscle]]s depress the larynx. (Innervated by ansa cervicalis)
* [[Omohyoid muscle]]s depress the larynx. (Ansa cervicalis)
* [[Sternohyoid muscle]]s depress the larynx. (Ansa cervicalis)
* [[Inferior constrictor muscle]]s. (CN X)
* [[Thyrohyoid muscle]]s elevates the larynx. (C1)
* [[Digastric]] elevates the larynx. (CN V<sub>3</sub>, CN VII)
* [[Stylohyoid]] elevates the larynx. (CN VII)
* [[Mylohyoid muscle|Mylohyoid]] elevates the larynx. (CN V<sub>3</sub>)
* [[Geniohyoid]] elevates the larynx. (C1)
* [[Hyoglossus]] elevates the larynx. (CN XII)
* [[Genioglossus]] elevates the larynx. (CN XII)

===Nerve supply===
The larynx is [[innervate]]d by branches of the [[vagus nerve]] on each side. Sensory innervation to the glottis and laryngeal vestibule is by the internal branch of the [[superior laryngeal nerve]]. The external branch of the superior laryngeal nerve innervates the [[cricothyroid muscle]].  Motor innervation to all other muscles of the larynx and sensory innervation to the subglottis is by the [[recurrent laryngeal nerve]]. While the sensory input described above is (general) visceral sensation (diffuse, poorly localized), the vocal cords also receives general somatic sensory innervation (proprioceptive and touch) by the superior laryngeal nerve.

Injury to the external branch of the superior laryngeal nerve causes weakened phonation because the vocal cords cannot be tightened. Injury to one of the recurrent laryngeal nerves produces [[hoarseness]], if both are damaged the voice may or may not be preserved, but breathing becomes difficult.

===Development===
In newborn infants, the larynx is initially at the level of the C2–C3 vertebrae, and is further forward and higher relative to its position in the adult body.<ref>{{cite web |url=http://www.utmb.edu/otoref/grnds/Reflux-Aspiration-050223/GERD-pedi-050223.htm |title=GERD and aspiration in the child: diagnosis and treatment |date=February 23, 2005 |work=Grand Rounds Presentation |publisher=UTMB Dept. of Otolaryngology |access-date=June 16, 2010 |archive-url=https://web.archive.org/web/20100601180918/http://www.utmb.edu/otoref/Grnds/Reflux-Aspiration-050223/GERD-pedi-050223.htm |archive-date=June 1, 2010 |url-status=dead }}</ref> The larynx descends as the child grows.<ref>{{Harvard citation no brackets|Laitman|Reidenberg|2009}}</ref><ref>{{Harvard citation no brackets|Laitman|Noden|Van De Water|2006}}</ref>