Larynx

The larynx (/ˈlærɪŋks/), commonly called the voice box, is an organ in the top of the neck of tetrapods involved in breathing, producing sound, and protecting the trachea against food aspiration. The larynx houses the vocal folds, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The word larynx (plural larynges) comes from a similar Ancient Greek word (λάρυγξ lárynx).[1]

Larynx
Larynx external en
Anatomy of the larynx, anterolateral view
Details
Pronunciation/ˈlærɪŋks/
Identifiers
Latinlarynx
MeSHD007830
TAA06.2.01.001
FMA55097
Anatomical terminology

Structure

The triangle-shaped larynx consists largely of cartilages that are attached to one another and to surroundings structures by muscles or by fibrous and elastic tissue components. It is lined by a ciliated mucous membrane. The cavity of the larynx extends from its triangle-shaped inlet the epiglottis 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 form two pairs of lateral folds that jut inward into its cavity. The upper folds are called the vestibular folds. They are also sometimes called the false vocal folds for the rather obvious reason that they play no part in vocalization. The lower pair serves as the vocal folds, which produce sounds needed for speech and other vocalizations. The vocal folds are sometimes called the true vocal folds or simply vocal cords (and often mistakenly spelt as, “vocal chords”). The slitlike space between the left and right vocal folds, called the rima glottidis, is the narrowest part of the larynx. The vocal folds and the space between them (rima glottidis) are together designated as the glottis. An endoscopic view of the vocal folds and related structures. The laryngeal cavity above the vestibular folds is called the vestibule. The very middle portion of the cavity between the vestibular and vocal folds 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 C3–C6 vertebrae. It connects the inferior part of the pharynx (hypopharynx) with the trachea. The laryngeal skeleton consists of six cartilages: three single (epiglottic, thyroid and cricoid) and three paired (arytenoid, corniculate, and cuneiform). 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.

Illu07 larynx02
Vocal cords abducted and adducted
Illu larynx
Basic parts of the human larynx

Cartilages

Posterior view of the larynx; disarticulated cartilages (left) and intrinsic muscles (right)

Gray950
Gray958

There are six cartilages, three unpaired and three paired, that support the mammalian larynx and form its skeleton.

Unpaired cartilages:

  • Thyroid cartilage: This forms the Adam's apple. It is usually larger in males than in females. The thyrohyoid membrane is a ligament associated with the thyroid cartilage that connects the thyroid cartilage with the hyoid bone.
  • 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 cartilages: Of the paired cartilages, the arytenoid cartilages are the most important because they influence the position and tension of the vocal folds. 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 intrinsic muscles are divided into respiratory and the phonatory muscles (the muscles of phonation). The respiratory muscles move the vocal cords apart and serve breathing. The phonatory muscles move the vocal cords together and serve the production of voice. The extrinsic, passing between the larynx and parts around; and intrinsic, confined entirely. The main respiratory muscles are the posterior cricoarytenoid muscles. The phonatory muscles are divided into adductors (lateral cricoarytenoid muscles, arytenoid muscles) and tensors (cricothyroid muscles, thyroarytenoid muscles).

Intrinsic

The intrinsic laryngeal muscles are responsible for controlling sound production.

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 folds 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 Ca2+-buffering profile that predicts their better ability to handle calcium changes in comparison to other muscles.[3] 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 Ca2+ (sarcoplasmic reticulum Ca2+-reuptake proteins, plasma membrane pumps, and cytosolic Ca2+-buffering proteins) are particularly elevated in laryngeal muscles, indicating their importance for the myofiber function and protection against disease, such as Duchenne muscular dystrophy.[4] Furthermore, differential levels of Orai1 in rat intrinsic laryngeal muscles and extraocular muscles over the limb muscle suggests a role for store operated 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 region. [trachea.]

Gray386
Extrinsic laryngeal muscles

Nerve supply

The larynx is innervated 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 fold also receives general somatic sensory innervation (proprioceptive and touch) by the superior laryngeal nerve.

Injury to the external laryngeal nerve causes weakened phonation because the vocal folds 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.[5] The larynx descends as the child grows.[6][7]

Function

Sound generation

Sound 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.

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, 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 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 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 (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 folds, and by moving the arytenoids forward or backward. This causes the pitch produced during phonation to rise or fall. In most males the vocal folds are longer and with a greater mass than most females' vocal folds, producing a lower pitch.

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

Other

Normal Epiglottis
Image of endoscopy

The most important role of the larynx is its protecting 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 folds, followed by the elevation of the larynx and the tight adduction (closing) of the vocal folds. The forced expiration that follows, assisted by tissue recoil and the muscles of expiration, blows the vocal folds 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 folds under significant strain.[8]

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 folds. Grunting while lifting heavy objects is the result of some air escaping through the adducted vocal folds ready for phonation.[8]

Abduction of the vocal folds is important during physical exertion. The vocal folds are separated by about 8 mm (0.31 in) during normal respiration, but this width is doubled during forced respiration.[8]

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 lungs, 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[9]

Clinical significance

Disorders

Larynx endo 3
Endoscopic image of an inflamed human larynx

There are several things that can cause a larynx to not function properly.[10] Some symptoms are hoarseness, loss of voice, pain in the throat or ears, and breathing difficulties. Larynx transplant is a rare procedure. The world's first successful operation took place in 1998 at the Cleveland Clinic,[11] and the second took place in October 2010 at the University of California Davis Medical Center in Sacramento.[12]

  • Acute laryngitis is the sudden inflammation and swelling of the larynx. It is caused by the common cold or by excessive shouting. It is not serious. Chronic laryngitis is caused by smoking, dust, frequent yelling, or prolonged exposure to polluted air. It is much more serious than acute laryngitis.
  • 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 folds is found on laryngoscopy.
  • Ulcers may be caused by the prolonged presence of an endotracheal tube.
  • Polyps and nodules are small bumps on the vocal folds caused by prolonged exposure to cigarette smoke and vocal misuse, respectively.
  • Two related types of cancer of the larynx, namely squamous cell carcinoma and verrucous carcinoma, are strongly associated with repeated exposure to cigarette smoke and alcohol.
  • Vocal cord paresis is weakness of one or both vocal folds that can greatly impact daily life.
  • Idiopathic laryngeal spasm.
  • Laryngopharyngeal reflux is a condition in which acid from the stomach irritates and burns the larynx. Similar damage can occur with gastroesophageal reflux disease (GERD).[13][14]
  • 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.
  • Laryngeal perichondritis, the inflammation of the perichondrium of laryngeal cartilages, causing airway obstruction.
  • Laryngeal paralysis is a condition seen in some mammals (including dogs) in which the larynx no longer opens as wide as required for the passage of air, and impedes respiration. In mild cases it can lead to exaggerated or "raspy" breathing or panting, and in serious cases can pose a considerable need for treatment.
  • Duchenne Muscular Dystrophy, intrinsic laryngeal muscles (ILM) are spared from the lack of dystrophin and may serve as a useful model to study the mechanisms of muscle sparing in neuromuscular diseases.[4] Dystrophic ILM presented a significant increase in the expression of calcium-binding proteins. The increase of calcium-binding proteins in dystrophic ILM may permit better maintenance of calcium homeostasis, with the consequent absence of myonecrosis. The results further support the concept that abnormal calcium buffering is involved in these neuromuscular diseases.[15]

Other animals

Kehlkopf Pferd
Cut through the larynx of a horse
(frontal section, posterior view)
hyoid bone; 2 epiglottis; 3 vestibular fold; 4 vocal fold; 5 ventricularis muscle; 6 ventricle of larynx; 7 vocalis muscle; 8 Thyroid Cartilage; 9 Cricoid Cartilage; 10 infraglottic cavity; 11 first tracheal cartilage; 12 trachea

Pioneering work on the structure and evolution of the larynx was carried out in the 1920s by the British comparative anatomist Victor Negus, culminating in his monumental work The Mechanism of the Larynx (1929). Negus, however, pointed out that the descent of the larynx reflected the reshaping and descent of the human tongue into the pharynx. This process is not complete until age six to eight years. Some researchers, such as Philip Lieberman, Dennis Klatt, Bart de Boer and Kenneth Stevens using computer-modeling techniques have suggested that the species-specific human tongue allows the vocal tract (the airway above the larynx) to assume the shapes necessary to produce speech sounds that enhance the robustness of human speech. Sounds such as the vowels of the words see and do, [i] and [u], (in phonetic notation) have been shown to be less subject to confusion in classic studies such as the 1950 Peterson and Barney investigation of the possibilities for computerized speech recognition.[16]

In contrast, though other species have low larynges, their tongues remain anchored in their mouths and their vocal tracts cannot produce the range of speech sounds of humans. The ability to lower the larynx transiently in some species extends the length of their vocal tract, which as Fitch showed creates the acoustic illusion that they are larger. Research at Haskins Laboratories in the 1960s showed that speech allows humans to achieve a vocal communication rate that exceeds the fusion frequency of the auditory system by fusing sounds together into syllables and words. The additional speech sounds that the human tongue enables us to produce, particularly [i], allow humans to unconsciously infer the length of the vocal tract of the person who is talking, a critical element in recovering the phonemes that make up a word.[16]

Non-mammals

Most tetrapod species possess a larynx, but its structure is typically simpler than that found in mammals. The cartilages surrounding the larynx are apparently a remnant of the original gill arches in fish, and are a common feature, but not all are always present. For example, the thyroid cartilage is found only in mammals. Similarly, only mammals possess a true epiglottis, although a flap of non-cartilagenous mucosa is found in a similar position in many other groups. In modern amphibians, the laryngeal skeleton is considerably reduced; frogs have only the cricoid and arytenoid cartilages, while salamanders possess only the arytenoids.[17]

Vocal folds are found only in mammals, and a few lizards. As a result, many reptiles and amphibians are essentially voiceless; frogs use ridges in the trachea to modulate sound, while birds have a separate sound-producing organ, the syrinx.[17]

History

The ancient Greek physician Galen first described the larynx, describing it as the "first and supremely most important instrument of the voice"[18]

Additional images

Slide14rom

Larynx. Deep dissection. Anterior view.

Slide36uru

Larynx. Deep dissection. Posterior view.

See also

References

Notes

  1. ^ "Larynx Etymology". Online Etymology Dictionary. Retrieved 25 October 2015.
  2. ^ Collectively, the transverse and oblique arytenoids are known as the interarytenoids.
  3. ^ Ferretti, R; Marques, MJ; Khurana, TS; Santo Neto, H (2015). "Expression of calcium-buffering proteins in rat intrinsic laryngeal muscles". Physiol Rep. 3: e12409. doi:10.14814/phy2.12409. PMC 4510619. PMID 26109185.
  4. ^ a b "Intrinsic laryngeal muscles are spared from myonecrosis in themdx mouse model of Duchenne muscular dystrophy". Muscle. 35: 349–353. doi:10.1002/mus.20697.
  5. ^ "GERD and aspiration in the child: diagnosis and treatment". Grand Rounds Presentation. UTMB Dept. of Otolaryngology. February 23, 2005. Retrieved June 16, 2010.
  6. ^ Laitman & Reidenberg 2009
  7. ^ Laitman, Noden & Van De Water 2006
  8. ^ a b c Seikel, King & Drumright 2010, Nonspeech laryngeal function, pp. 223–225
  9. ^ Ferretti, R; Marques, MJ; Khurana, TS; Santo Neto, H (2015). "Expression of calcium-buffering proteins in rat intrinsic laryngeal muscles". Physiol Rep. 3: e12409. doi:10.14814/phy2.12409. PMC 4510619. PMID 26109185.
  10. ^ Laitman & Reidenberg 1993
  11. ^ Jensen, Brenda (January 21, 2011). "Rare transplant gives California woman a voice for the first time in a decade".
  12. ^ Johnson, Avery (January 21, 2011). "Woman Finds Her Voice After Rare Transplant". Wall Street Journal. Retrieved 4 September 2012.
  13. ^ Laitman & Reidenberg 1997
  14. ^ Lipan, Reidenberg & Laitman 2006
  15. ^ "Sarcoplasmic-endoplasmic-reticulum Ca2+-ATPase and calsequestrin are overexpressed in spared intrinsic laryngeal muscles of dystrophin-deficientmdxmice". Muscle & Nerve. 39: 609–615. doi:10.1002/mus.21154.
  16. ^ a b Lieberman 2006
  17. ^ a b Romer & Parsons 1977, pp. 214–215, 336
  18. ^ Hydman, Jonas (2008). Recurrent laryngeal nerve injury. Stockholm. p. 8. ISBN 978-91-7409-123-6.

Sources

  • Laitman, J.T.; Noden, D.M.; Van De Water, T.R. (2006). "Formation of the larynx: from homeobox genes to critical periods". In Rubin, J.S.; Sataloff, R.T.; Korovin, G.S. (eds.). Diagnosis & Treatment Voice Disorders. San Diego: Plural. pp. 3–20. ISBN 9781597560078. OCLC 63279542.
  • Laitman, J.T.; Reidenberg, J.S. (1993). "Specializations of the human upper respiratory and upper digestive tract as seen through comparative and developmental anatomy". Dysphagia. 8 (4): 318–325. doi:10.1007/BF01321770. PMID 8269722.
  • Laitman, J.T.; Reidenberg, J.S. (1997). "The human aerodigestive tract and gastroesophageal reflux: An evolutionary perspective". Am. J. Med. 103 (Suppl 5A): 3–11. doi:10.1016/s0002-9343(97)00313-6. PMID 9422615.
  • Laitman, J.T.; Reidenberg, J.S. (2009). "The evolution of the human larynx: Nature's great experiment". In Fried, M.P.; Ferlito, A. (eds.). The Larynx (3rd ed.). San Diego: Plural. pp. 19–38. ISBN 1597560626. OCLC 183609898.
  • Lieberman, P. (2006). Toward an Evolutionary Biology of Language. Harvard University Press. ISBN 0-674-02184-3. OCLC 62766735.
  • Lipan, M.; Reidenberg, J.S; Laitman, J.T. (2006). "The anatomy of reflux: A growing health problem affecting structures of the head and neck". Anat Rec B New Anat. 289 (6): 261–270. doi:10.1002/ar.b.20120. OCLC 110307385. PMID 17109421.
  • Romer, A.S.; Parsons, T.S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. ISBN 0-03-910284-X.
  • Seikel, J.A.; King, D.W.; Drumright, D.G. (2010). Anatomy & Physiology for Speech, Language, and Hearing (4th ed.). Delmar, NY: Cengage Learning. ISBN 1-4283-1223-4.
Angioedema

Angioedema is an area of swelling of the lower layer of skin and tissue just under the skin or mucous membranes. The swelling may occur in the face, tongue, larynx, abdomen, or arms and legs. Often it is associated with hives, which are swelling within the upper skin. Onset is typically over minutes to hours.The underlying mechanism typically involves histamine or bradykinin. The version related to histamine is due to an allergic reaction to agents such as insect bites, foods, or medications. The version related to bradykinin may occur due to an inherited problem known as C1 esterase inhibitor deficiency, medications known as angiotensin converting enzyme inhibitors, or a lymphoproliferative disorder.Efforts to protect the airway may include intubation or cricothyroidotomy. Histamine related angioedema can be treated with antihistamines, corticosteroids, and epinephrine. In those with bradykinin related disease a C1 esterase inhibitor, ecallantide, or icatibant may be used. Fresh frozen plasma may be used instead. In the United States the disease affects about 100,000 people a year.

Electrolarynx

An electrolarynx, sometimes referred to as a "throat back", is a medical device about the size of a small electric razor used to produce clearer speech by those people who have lost their voicebox, usually due to cancer of the larynx. The most common device is a handheld, battery-operated device placed under the mandible which produces vibrations to allow speech. Earlier non-electric devices were called mechanical larynxes. Along with developing esophageal voice, robotic voice or undergoing a surgical procedure, the electrolarynx serves as a mode of speech recovery for laryngectomy patients.

Epiglottis

The epiglottis is a flap in the throat that keeps food from entering the windpipe and the lungs. The flap is made of elastic cartilage covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. It stands open during breathing, allowing air into the larynx. During swallowing, it closes to prevent aspiration and forcing the swallowed liquids or food to go along the esophagus instead. It is thus the valve that diverts passage to either the trachea or the esophagus.

The epiglottis gets its name from being above the glottis (epi- + glottis).

There are taste buds on the epiglottis.

Glottis

The glottis is the opening between the vocal folds (the rima glottidis).

Human voice

The human voice consists of sound made by a human being using the vocal tract, such as talking, singing, laughing, crying, screaming, etc. The human voice frequency is specifically a part of human sound production in which the vocal folds (vocal cords) are the primary sound source. (Other sound production mechanisms produced from the same general area of the body involve the production of unvoiced consonants, clicks, whistling and whispering.)

Generally speaking, the mechanism for generating the human voice can be subdivided into three parts; the lungs, the vocal folds within the larynx (voice box), and the articulators. The lung, the "pump" must produce adequate airflow and air pressure to vibrate vocal folds. The vocal folds (vocal cords) then vibrate to use airflow from the lungs to create audible pulses that form the laryngeal sound source. The muscles of the larynx adjust the length and tension of the vocal folds to ‘fine-tune’ pitch and tone. The articulators (the parts of the vocal tract above the larynx consisting of tongue, palate, cheek, lips, etc.) articulate and filter the sound emanating from the larynx and to some degree can interact with the laryngeal airflow to strengthen it or weaken it as a sound source.

The vocal folds, in combination with the articulators, are capable of producing highly intricate arrays of sound. The tone of voice may be modulated to suggest emotions such as anger, surprise, fear, happiness or sadness. The human voice is used to express emotion, and can also reveal the age and sex of the speaker. Singers use the human voice as an instrument for creating music.

Laryngeal cancer

Laryngeal cancer are mostly squamous cell carcinomas, reflecting their origin from the skin of the larynx.

Cancer can develop in any part of the larynx, but the cure rate is affected by the location of the tumour. For the purposes of tumour staging, the larynx is divided into three anatomical regions: the glottis (true vocal cords, anterior and posterior commissures); the supraglottis (epiglottis, arytenoids and aryepiglottic folds, and false cords); and the subglottis.

Most laryngeal cancers originate in the glottis. Supraglottic cancers are less common, and subglottic tumours are least frequent.

Laryngeal cancer may spread by direct extension to adjacent structures, by metastasis to regional cervical lymph nodes, or more distantly, through the blood stream. Distant metastases to the lung are most common. In 2013 it resulted in 88,000 deaths up from 76,000 deaths in 1990. Five year survival rates in the United States are 60%.

Laryngeal consonant

Laryngeal consonants (a term often used interchangeably with guttural consonants) are consonants with their primary articulation in the larynx. The laryngeal consonants comprise the pharyngeal consonants (including the epiglottals), the glottal consonants, and for some languages uvular consonants.The term laryngeal is often taken to be synonymous with glottal, but the larynx consists of more than just the glottis (vocal folds): it also includes the epiglottis and aryepiglottic folds. In a broad sense, therefore, laryngeal articulations include the radical consonants, which involve the root of the tongue. The diversity of sounds produced in the larynx is the subject of ongoing research, and the terminology is evolving.

The term laryngeal consonant is also used for laryngealized consonants articulated in the upper vocal tract, such as Arabic 'emphatics' and Korean 'tense' consonants.

Laryngeal papillomatosis

Laryngeal papillomatosis, also known as recurrent respiratory papillomatosis or glottal papillomatosis, is a rare medical condition in which benign tumors (papilloma) form along the aerodigestive tract. There are two variants based on the age of onset: juvenile and adult laryngeal papillomatosis. The tumors are caused by human papillomavirus (HPV) infection of the throat. The tumors may lead to narrowing of the airway, which may cause vocal changes or airway obstruction. Laryngeal papillomatosis is initially diagnosed through indirect laryngoscopy upon observation of growths on the larynx and can be confirmed through a biopsy. Treatment for laryngeal papillomatosis aims to remove the papillomas and limit their recurrence. Due to the recurrent nature of the virus, repeated treatments usually are needed. Laryngeal papillomatosis is primarily treated surgically, though supplemental nonsurgical and/or medical treatments may be considered in some cases. The evolution of laryngeal papillomatosis is highly variable. Though total recovery may be observed, it is often persistent despite treatment. The number of new cases of laryngeal papillomatosis cases is at approximately 4.3 cases per 100,000 children and 1.8 cases per 100,000 adults annually.

Laryngeal ventricle

The laryngeal ventricle, (also called the ventricle of the larynx, laryngeal sinus, or Morgagni's sinus) is a fusiform fossa, situated between the vestibular and vocal folds on either side, and extending nearly their entire length. There is also a sinus of Morgagni in the pharynx.

The fossa is bounded, above, by the free crescentic edge of the vestibular ligament; below, by the straight margin of the vocal fold and laterally, by the mucous membrane covering the corresponding thyroarytenoid muscle.

The anterior part of the ventricle leads up by a narrow opening into a pouch-like diverticulum, a mucous membranous sac of variable size called the appendix of the laryngeal ventricle. The appendix (also called the laryngeal saccule, pouch or Hilton's pouch) extends vertically from the laryngeal ventricle. It runs between the vestibular fold, thyroarytenoid muscle, and thyroid cartilage, and is conical, bending slightly backward. It is covered in roughly seventy mucous glands. The muscles surrounding the appendix compress it until mucus is secreted to lubricate the vocal folds.

Laryngitis

Laryngitis is inflammation of the larynx (voice box). Symptoms often include a hoarse voice and may include fever, cough, pain in the front of the neck, and trouble swallowing. Typically, these last under two weeks.Laryngitis is categorised as acute if it lasts less than three weeks and chronic if symptoms last more than three weeks. Acute cases usually occur as part of a viral upper respiratory tract infection. Other infections and trauma such as from coughing are other causes. Chronic cases may occur due to smoking, tuberculosis, allergies, acid reflux, rheumatoid arthritis, or sarcoidosis. The underlying mechanism involves irritation of the vocal cords.Concerning signs that may require further investigation include stridor, history of radiation therapy to the neck, trouble swallowing, duration of more than three weeks, and a history of smoking. If concerning signs are present the vocal cords should be examined via laryngoscopy. Other conditions that can produce similar symptoms include epiglottitis, croup, inhaling a foreign body, and laryngeal cancer.The acute form generally resolves without specific treatment. Resting the voice and sufficient fluids may help. Antibiotics generally do not appear to be useful in the acute form. The acute form is common while the chronic form is not. The chronic form occurs most often in middle age and is more common in men than women.

Laryngopharyngeal reflux

Laryngopharyngeal reflux (LPR), also known as extraesophageal reflux disease (EERD), silent reflux, and supra-esophageal reflux, is the retrograde flow of gastric contents into the larynx, oropharynx and/or the nasopharynx. LPR causes respiratory symptoms such as cough and wheezing and is often associated with head and neck complaints such as dysphonia, globus pharyngis, and dysphagia. LPR may play a role in other diseases, such as sinusitis, otitis media, and rhinitis, and can be a comorbidity of asthma. While LPR is commonly used interchangeably with gastroesophageal reflux disease (GERD), it presents with a different pathophysiology.LPR reportedly affects approximately 30% of the U.S. population. However, LPR occurs in as many as 50% of individuals with voice disorders.

Pharynx

The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity and above the oesophagus and larynx, or the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, though its structure varies across species.

In humans, the pharynx is part of the digestive system and the conducting zone of the respiratory system. (The conducting zone—which also includes the nostrils of the nose, the larynx, trachea, bronchi, and bronchioles—filters, warms and moistens air and conducts it into the lungs). The pharynx makes up the part of the throat immediately behind the nasal cavity, behind the mouth and above the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx, oropharynx, and laryngopharynx. It is also important in vocalization.

In humans,two sets of pharyngeal muscles form the pharynx and determine the shape of its lumen. They are arranged as an inner layer of longitudinal muscles and an outer circular layer.

Phonation

The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the definition used among those who study laryngeal anatomy and physiology and speech production in general. Phoneticians in other subfields, such as linguistic phonetics, call this process voicing, and use the term phonation to refer to any oscillatory state of any part of the larynx that modifies the airstream, of which voicing is just one example. Voiceless and supra-glottal phonations are included under this definition.

Respiratory tract

In humans, the respiratory tract is the part of the anatomy of the respiratory system involved with the process of respiration. Air is breathed in through the nose or the mouth. In the nasal cavity, a layer of mucous membrane acts as a filter and traps pollutants and other harmful substances found in the air. Next, air moves into the pharynx, a passage that contains the intersection between the esophagus and the larynx. The opening of the larynx has a special flap of cartilage, the epiglottis, that opens to allow air to pass through but closes to prevent food from moving into the airway.

From the larynx, air moves into the trachea and down to the intersection that branches to form the right and left primary (main) bronchi. Each of these bronchi branch into secondary (lobar) bronchi that branch into tertiary (segmental) bronchi that branch into smaller airways called bronchioles that eventually connect with tiny specialized structures called alveoli that function in gas exchange.

The lungs which are located in the thoracic cavity, are protected from physical damage by the rib cage. At the base of the lungs is a sheet of skeletal muscle called the diaphragm. The diaphragm separates the lungs from the stomach and intestines. The diaphragm is also the main muscle of respiration involved in breathing, and is controlled by the sympathetic nervous system.

The lungs are encased in a serous membrane that folds in on itself to form the pleurae – a two-layered protective barrier. The inner visceral pleura covers the surface of the lungs, and the outer parietal pleura is attached to the inner surface of the thoracic cavity. The pleurae enclose a cavity called the pleural cavity that contains pleural fluid. This fluid is used to decrease the amount of friction that lungs experience during breathing.

Throat

In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the pharynx and larynx. An important section of it is the epiglottis, which is a flap separating the esophagus from the trachea (windpipe) preventing food and drink being inhaled into the lungs. The throat contains various blood vessels, pharyngeal muscles, the nasopharyngeal tonsil, the tonsils, the palatine uvula, the trachea, the esophagus, and the vocal cords. Mammal throats consist of two bones, the hyoid bone and the clavicle. The "throat" is sometimes thought to be synonymous for the isthmus of the fauces.It works with the mouth, ears and nose, as well as a number of other parts of the body. Its pharynx is connected to the mouth, allowing speech to occur, and food and liquid to pass down the throat. It is joined to the nose by the nasopharynx at the top of the throat, and to ear by its Eustachian tube. The throat's trachea carries inhaled air to the bronchi of the lungs. The esophagus carries food through the throat to the stomach. Adenoids and tonsils help prevent infection and are composed of lymph tissue. The larynx contains vocal cords, the epiglottis (preventing food/liquid inhalation), and an area known as the subglottic larynx—the narrowest section of the upper part of the throat. In the larynx, the vocal cords consist of two membranes that act according to the pressure of the air.

Trachea

The trachea, colloquially called the windpipe, is a cartilaginous tube that connects the pharynx and larynx to the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends from the larynx and branches into the two primary bronchi. At the top of the trachea the cricoid cartilage attaches it to the larynx. This is the only complete tracheal ring, the others being incomplete rings of reinforcing cartilage. The trachealis muscle joins the ends of the rings and these are joined vertically by bands of fibrous connective tissue – the annular ligaments of trachea. The epiglottis closes the opening to the larynx during swallowing.

The trachea develops in the second month of development. It is lined with an epithelium that has goblet cells which produce protective mucins (see Respiratory epithelium). An inflammatory condition, also involving the larynx and bronchi, called croup can result in a barking cough. A tracheotomy is often performed for ventilation in surgical operations where needed. Intubation is also carried out for the same reason by the inserting of a tube into the trachea. From 2008, operations have experimentally transplanted a windpipe grown by stem cells, and synthetic windpipes; however, a successful method for this method of transplant does not currently exist and development of such a method remains theoretically daunting.The word "trachea" is used to define a very different organ in invertebrates than in vertebrates. Insects have an open respiratory system made up of spiracles, tracheae, and tracheoles to transport metabolic gases to and from tissues.

Vocal cord paresis

Vocal fold paresis, also known as recurrent laryngeal nerve paralysis or vocal fold paralysis, is an injury to one or both recurrent laryngeal nerves (RLNs), which control all muscles of the larynx except for the cricothyroid muscle. The RLN is important for speaking, breathing and swallowing.The primary larynx-related functions of the mainly efferent nerve fiber RLN, include the transmission of nerve signals to the muscles responsible for regulation of the vocal folds' position and tension to enable vocalization, as well as the transmission of sensory nerve signals from the mucous membrane of the larynx to the brain.

A unilateral injury of the nerve typically results in hoarseness caused by a reduced mobility of one of the vocal folds. It may also cause minor shortages of breath as well as aspiration problems especially concerning liquids. A bilateral injury causes the vocal folds to impair the air flow resulting in breathing problems, stridor and snoring sounds, and fast physical exhaustion. This strongly depends on the median or paramedian position of the paralyzed vocal folds. Hoarseness rarely occurs in bilaterally paralyzed vocal folds.

Voice Quality Symbols

Voice Quality Symbols (VoQS) are a set of phonetic symbols used to transcribe disordered speech for what in speech pathology is known as "voice quality". This phrase only means what it does in phonetics (that is, phonation) in a few causes. In others it means secondary articulation.

VoQS symbols are normally combined with curly braces that span a section of speech, just as with prosody notation in the extended IPA. The symbols may be modified with a digit to convey relative degree of the quality. For example, ⟨V!⟩ is used for harsh voice, and {3V! ... 3V!} indicates that the intervening speech is very harsh. ⟨L̞⟩ indicates a lowered larynx. Thus, {L̞1V! ... 1V!L̞} indicates that the intervening speech is less harsh with a lowered larynx.

VoQS use mostly IPA or extended IPA diacritics on capital letters for the element being modified: V for 'voice'/articulation, L for 'larynx', and J for 'jaw'. Degree is marked 1 for slight, 2 for moderate, and 3 for extreme.

Voicelessness

In linguistics, voicelessness is the property of sounds being pronounced without the larynx vibrating. Phonologically, it is a type of phonation, which contrasts with other states of the larynx, but some object that the word phonation implies voicing and that voicelessness is the lack of phonation.

The International Phonetic Alphabet has distinct letters for many voiceless and modally voiced pairs of consonants (the obstruents), such as [p b], [t d], [k ɡ], [q ɢ], [f v], and [s z]. Also, there are diacritics for voicelessness, U+0325  ̥ COMBINING RING BELOW and U+030A  ̊ COMBINING RING ABOVE, which is used for letters with a descender. Diacritics are typically used with letters for prototypically voiced sounds, such as vowels and sonorant consonants: [ḁ], [l̥], [ŋ̊].

Anatomy of the larynx
Cartilage
Ligaments/folds
Laryngeal cavity
Laryngeal muscles
Other

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