larynx n : a cartilaginous structure at the top of the trachea; contains elastic vocal cords that are the source of the vocal tone in speech [syn: voice box] [also: larynges (pl)]
The larynx (plural larynges), colloquially known as the voicebox, is an organ in the neck of mammals involved in protection of the trachea and sound production. The larynx houses the vocal folds, and is situated just below where the tract of the pharynx splits into the trachea and the esophagus
FunctionSound is generated in the larynx, and that is where pitch and volume are manipulated. The strength of expiration from the lungs also contributes to loudness, and is necessary for the vocal folds to produce speech .
Fine manipulation of the larynx is used in a great way 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, lips, 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.
During swallowing, the backward motion of the tongue forces the epiglottis over the laryngeal opening to prevent swallowed material from entering the lungs; the larynx is also pulled upwards to assist this process. Stimulation of the larynx by ingested matter produces a strong cough reflex to protect the lungs.
The vocal folds 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 fold length and tension can be controlled by rocking the thyroid cartilage forward and backward on the cricoid cartilage, and by manipulating the tension of the muscles within the vocal folds. This causes the pitch produced during phonation to rise or fall. In most males the vocal cords are longer, producing a deeper pitch.
The vocal apparatus consists of two pairs of mucosal folds. These folds are false vocal cords(vestibular folds) and true vocal cords(folds). The false vocal cords are covered by respiratory epithelium, while the true vocal cords are covered by stratified squamous epithelium. The false vocal cords are not responsible for sound production, but rather for resonance. These false vocal cords do not contain muscle, while the true vocal cords do have skeletal muscle.
InnervationThe larynx is innervated by branches of the vagus nerve (CN X) on one side. Sensory innervation to the glottis and supraglottis 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.
Injury to the external 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 is completely lost and breathing becomes difficult.
Muscles associated with the larynx
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.
Descended larynxIn most animals, including infant humans and apes, the larynx is situated very high in the throat — a position that allows it to couple more easily with the nasal passages, so that breathing and eating are not done with the same apparatus. However, some aquatic mammals, large deer, and adult humans have descended larynges. An adult human cannot raise the larynx enough to directly couple it to the nasal passage.
Some linguists have suggested that the descended larynx, by extending the length of the vocal tract and thereby increasing the variety of sounds humans could produce, was a critical element in the development of speech and language. Others cite the presence of descended larynges in non-linguistic animals, as well as the ubiquity of nonverbal communication and language among humans, as counterevidence against this claim.
Disorders of the larynx
There are several things that can cause a larynx to not function properly. Some symptoms are hoarseness, loss of voice, pain in the throat or ears, and breathing difficulties.
- Presbylarynx is a condition in which age-related atrophy of the soft tissues of the larynx results in weak voice and restricted vocal range and stamina. Bowing of the anterior portion of the vocal cords is found on laryngoscopy.
- Vocal cord paresis is weakness of one or both vocal folds that can greatly impact daily life.
- Idiopathic larangyal spasm
- Laryngomalacia is a very common condition of infancy, in which the soft, immature cartilage of the upper larynx collapses inward during inhalation, causing airway obstruction.
- The world's first successful larynx transplant took place in 1999 at the Cleveland Clinic.
CartilagesThere are six in all, three unpaired and three paired.The cartilages of the larynx are the thyroid, cricoid, epiglottis, arytenoids, corniculate, and the cuneiforms.
Image:Illu bronchi lungs.jpg|Bronchi, bronchial tree, and lungs Image:Illu larynx.jpg|Larynx Image:Larynx external en.svg|The ligaments of the larynx. Antero-lateral view. Image:Larynx endo 2.jpg|Endoscopic image of larynx seen at the time of intubation of the esophagus during gastroscopy.
ReferencesSpeech and Hearing Science: Anatomy and Physiology 3rd edition. Willard R. Zemlin. 1988. Prentice-Hall, Inc. Englewood Cliffs, New Jersey. ISBN 0-13-827429-0
larynx in Arabic: حنجرة
larynx in Bosnian: Grkljan
larynx in Bulgarian: Ларинкс
larynx in Catalan: Laringe
larynx in Czech: Hrtan
larynx in German: Kehlkopf
larynx in Dhivehi: އަޑު ފޮށި
larynx in Estonian: Kõri
larynx in Spanish: Laringe
larynx in Esperanto: Laringo
larynx in Basque: Laringe
larynx in Persian: حنجره
larynx in French: Larynx
larynx in Croatian: Grkljan
larynx in Ido: Laringo
larynx in Indonesian: Laring
larynx in Italian: Laringe
larynx in Hebrew: בית הקול
larynx in Latin: Larynx
larynx in Lithuanian: Gerklos
larynx in Macedonian: Грклан
larynx in Dutch: Strottenhoofd
larynx in Japanese: 喉頭
larynx in Norwegian: Strupehode
larynx in Polish: Krtań
larynx in Portuguese: Laringe
larynx in Romanian: Laringe
larynx in Russian: Гортань
larynx in Simple English: Larynx
larynx in Slovak: Hrtan
larynx in Finnish: Kurkunpää
larynx in Swedish: Struphuvud
larynx in Tamil: குரல்வளை
larynx in Thai: กล่องเสียง
larynx in Turkish: Gırtlak
larynx in Ukrainian: Гортань
larynx in Võro: Kurgusõlm
larynx in Yiddish: שטימע קעסטל
larynx in Chinese: 喉頭