Editing Larynx (section)

== Function ==

===Sound generation===
Sound is generated in the larynx, and that is where [[pitch (music)|pitch]] and [[loudness|volume]] are manipulated. The strength of [[exhalation|expiration]] from the lungs also contributes to loudness.

Manipulation of the larynx is used to generate a source sound with a particular fundamental frequency, or pitch.  This source sound is altered as it travels through the [[vocal tract]], configured differently based on the position of the [[tongue]], [[lip]]s, [[mouth]], and [[pharynx]].  The process of altering a source sound as it passes through the filter of the vocal tract creates the many different vowel and consonant sounds of the world's languages as well as tone, certain realizations of stress and other types of linguistic prosody. The larynx also has a similar function to the lungs in creating pressure differences required for sound production; a constricted larynx can be raised or lowered affecting the volume of the oral cavity as necessary in glottalic consonants.

The vocal cords can be held close together (by adducting the arytenoid cartilages) so that they vibrate (see [[phonation]]). The muscles attached to the arytenoid cartilages control the degree of opening. Vocal cord length and tension can be controlled by rocking the [[thyroid cartilage]] forward and backward on the [[cricoid cartilage]] (either directly by contracting the cricothyroids or indirectly by changing the vertical position of the larynx), by manipulating the tension of the muscles within the vocal cords, and by moving the arytenoids forward or backward. This causes the pitch produced during [[phonation]] to rise or fall. In most males the vocal cords are longer and have a greater mass than most females' vocal cords, producing a lower pitch.

The vocal apparatus consists of two pairs of folds, the [[vestibular fold]]s (false vocal cords) and the true [[vocal cords]]. The vestibular folds are covered by [[respiratory epithelium]], while the vocal cords are covered by [[stratified squamous epithelium]]. The vestibular folds are not responsible for sound production, but rather for resonance. The exceptions to this are found in [[Overtone singing#Tibet|Tibetan chanting]] and Kargyraa, a style of [[Tuvan throat singing]]. Both make use of the vestibular folds to create an undertone. These false vocal cords do not contain muscle, while the true vocal cords do have skeletal muscle.

===Other===
[[File:Normal Epiglottis.jpg|thumb|Image of endoscopy]]
The most important role of the larynx is its protective function, the prevention of foreign objects from entering the lungs by [[coughing]] and other reflexive actions.  A cough is initiated by a deep inhalation through the vocal cords, followed by the elevation of the larynx and the tight adduction (closing) of the vocal cords.  The forced expiration that follows, assisted by tissue recoil and the muscles of expiration, blows the vocal cords apart, and the high pressure expels the irritating object out of the throat.  Throat clearing is less violent than coughing, but is a similar increased respiratory effort countered by the tightening of the laryngeal musculature.  Both coughing and throat clearing are predictable and necessary actions because they clear the respiratory passageway, but both place the vocal cords under significant strain.<ref name="Seikel-etal-2010-223">{{Harvard citation no brackets|Seikel|King|Drumright|2010|loc=Nonspeech laryngeal function, pp. 223–225}}</ref>

Another important role of the larynx is abdominal fixation, a kind of [[Valsalva maneuver]] in which the lungs are filled with air in order to stiffen the thorax so that forces applied for lifting can be translated down to the legs.  This is achieved by a deep inhalation followed by the adduction of the vocal cords.  Grunting while lifting heavy objects is the result of some air escaping through the adducted vocal cords ready for [[phonation]].<ref name="Seikel-etal-2010-223" />

Abduction of the vocal cords is important during physical exertion.  The vocal cords are separated by about {{Convert|8|mm|abbr=on}} during normal respiration, but this width is doubled during forced respiration.<ref name="Seikel-etal-2010-223" />

During [[swallowing]], elevation of the posterior portion of the tongue levers (inverts) the epiglottis over the glottis' opening to prevent swallowed material from entering the larynx which leads to the [[lung]]s, and provides a path for a food or liquid bolus to "slide" into the esophagus; the hyo-laryngeal complex is also pulled upwards to assist this process. Stimulation of the larynx by aspirated food or liquid produces a strong [[cough]] [[reflex]] to protect the lungs.

In addition, intrinsic laryngeal muscles are spared from some muscle wasting disorders, such as [[Duchenne muscular dystrophy]],  may facilitate the development of novel strategies for the prevention and treatment of muscle wasting in a variety of clinical scenarios. ILM have a calcium regulation system profile suggestive of a better ability to handle calcium changes in comparison to other muscles, and this may provide a mechanistic insight for their unique pathophysiological properties<ref name="Expression of calcium-buffering pro"/>