Larynx
Endoscopic image of larynx

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. Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an instrument called an endoscope. In Biology, an organ ( Latin: organum, "instrument tool" from Greek όργανον - organon "organ instrument The neck is the part of the Body on many limbed Vertebrates that distinguishes the head from the Torso or trunk Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands The traceartes, or windpipe, is a tube that has an inner diameter of about 20-25 mm and a length of about 10-16 cm in humans The larynx houses the vocal folds, and is situated just below where the tract of the pharynx splits into the trachea and the esophagus

Contents 1 Function 2 Innervation 3 Muscles associated with the larynx 4 Descended larynx 5 Disorders of the larynx 6 Cartilages 7 Images 8 See also 9 References

Function

Sound is generated in the larynx, and that is where pitch and volume are manipulated. The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of Mucous membrane stretched horizontally across the Larynx. The pharynx (plural pharynges) is the part of the Neck and Throat situated immediately Posterior to (behind the Mouth and Nasal The esophagus or oesophagus (see American and British English spelling differences) sometimes known as the gullet, is an organ in Pitch represents the perceived Fundamental frequency of a sound Loudness is the quality of a Sound that is the primary psychological correlate of physical strength (amplitude The strength of expiration from the lungs also contributes to loudness, and is necessary for the vocal folds to produce speech ^[1].

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 vocal tract is that cavity in animals and humans where sound that is produced at the sound source ( Larynx in mammals syrinx in birds is filtered The tongue is the large bundle of Skeletal muscles on the floor of the Mouth that manipulates Food for chewing and swallowing (deglutition The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up The pharynx (plural pharynges) is the part of the Neck and Throat situated immediately Posterior to (behind the Mouth and Nasal 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. Swallowing, known scientifically as deglutition is the process in the human or animal body that makes something pass from the Mouth, to the Pharynx, into lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive Stimulation of the larynx by ingested matter produces a strong cough reflex to protect the lungs. In Medicine, a cough ( Latin: tussis) is a sudden and often repetitively occurring defence Reflex which helps to clear the large breathing passages A reflex action, also known as a reflex, is an involuntary and almost instant movement in response to stimulus.

The vocal folds can be held close together (by adducting the arytenoid cartilages), so that they vibrate (see phonation). Phonation has slightly different meanings depending on the subfield of Phonetics. 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. The thyroid cartilage is the largest of the nine Cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains The cricoid cartilage, or simply cricoid (from the Greek krikoeides meaning "ring-shaped" is the only complete ring of Cartilage around the This causes the pitch produced during phonation to rise or fall. Phonation has slightly different meanings depending on the subfield of Phonetics. 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.

Innervation

The larynx is innervated by branches of the vagus nerve (CN X) on one side. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. The vagus nerve (ˈveɪˌgəs (VĀ-gəs (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired Cranial nerves, and is the Sensory innervation to the glottis and supraglottis is by the internal branch of the superior laryngeal nerve. The superior laryngeal nerve is a branch of the Vagus nerve. It arises from the middle of the Ganglion nodosum and in its course receives a branch from the Superior The external branch of the superior laryngeal nerve innervates the cricothyroid muscle. The cricothyroid muscle attaches to the anterolateral aspect of the Cricoid and the inferior Cornu and lower Lamina of the Thyroid cartilage Motor innervation to all other muscles of the larynx and sensory innervation to the subglottis is by the recurrent laryngeal nerve. The recurrent (inferior laryngeal nerve is a branch of the vagus nerve (tenth Cranial nerve) that supplies motor function and sensation to the Larynx (voice box

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

• Cricothyroid muscle lengthens and stretches the vocal cords. The cricothyroid muscle attaches to the anterolateral aspect of the Cricoid and the inferior Cornu and lower Lamina of the Thyroid cartilage
• Posterior cricoarytenoid muscle abducts the vocal cords. The posterior cricoarytenoid muscles are extremely small paired muscles that extend from the posterior Cricoid cartilage to the Arytenoid cartilages in the Larynx
• Lateral cricoarytenoid muscle adducts the vocal cords. The lateral cricoarytenoid muscles extend from the lateral Cricoid cartilage to the ipsilateral Arytenoid cartilage.
• Thyroarytenoid muscle (also called vocalis muscle) shortens vocal cords. The Thyroarytenoid is a broad thin muscle which lies parallel with and lateral to the Vocal fold, and supports the wall of the ventricle and its appendix
• Transverse arytenoid muscle adducts the vocal folds. The arytenoid /ærɪˈtiːnɔɪd/ is a single muscle filling up the posterior concave surfaces of the arytenoid cartilages

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 larynx

In 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. Marine mammals are a diverse group of roughly 120 species of Mammal that are primarily Ocean -dwelling or depend on the ocean for food A deer is a Ruminant Mammal belonging to the family Cervidae. 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. Speech refers to the processes associated with the production and perception of Sounds used in Spoken language. A language is a dynamic set of visual auditory or tactile Symbols of Communication and the elements used to manipulate them 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. Nonverbal communication (NVC is usually understood as the process of Communication through sending and receiving Wordless messages

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.

• Acute laryngitis is the sudden inflammation and swelling of the larynx. Laryngitis is an Inflammation of the Larynx. It causes hoarse voice or the complete loss of the voice because of irritation to the Vocal folds 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. Laryngitis is an Inflammation of the Larynx. It causes hoarse voice or the complete loss of the voice because of irritation to the Vocal folds 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 cords is found on laryngoscopy.

• Ulcers may be caused by the prolonged presence of an endotracheal tube. Ulcers are healing wounds that develop on the skin mucous membranes or eye

• Polyps and nodules are small bumps on the vocal cords caused by prolonged exposure to cigarette smoke and vocal overuse, respectively. A polyp is an abnormal growth of tissue ( Tumor) projecting from a Mucous membrane. In Medicine, a nodule refers to a relatively hard roughly spherical abnormal structure The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of Mucous membrane stretched horizontally across the Larynx. A cigarette ( French "small Cigar " from cigar + -ette) is a product consumed through Smoking and manufactured

• 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. Laryngeal cancer may also be called cancer of the larynx or laryngeal carcinoma. In Medicine, squamous cell carcinoma (SCC is a form of Cancer of the Carcinoma type that may occur in many different organs including the Skin Verrucous carcinoma is a variant of Squamous cell carcinoma. This form of cancer is often seen in those who chew Tobacco or use Snuff, so much so that

• Vocal cord paresis is weakness of one or both vocal folds that can greatly impact daily life. Vocal cord paresis (or paralysis) is weakness of one or both Vocal folds that can greatly impact Daily life, Employment, job choice Social

• 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. Laryngomalacia (literally "soft Larynx " is a very common condition of infancy in which the soft immature Cartilage of the upper larynx collapses inward

• The world's first successful larynx transplant took place in 1999 at the Cleveland Clinic. The Cleveland Clinic (formally known as the Cleveland Clinic Foundation) is a multispecialty academic medical center located in Cleveland, Ohio, ^[2]

Cartilages

There are six in all, three unpaired and three paired. The cartilages of the larynx are the thyroid, cricoid, epiglottis, arytenoids, corniculate, and the cuneiforms. The thyroid cartilage is the largest of the nine Cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains The cricoid cartilage, or simply cricoid (from the Greek krikoeides meaning "ring-shaped" is the only complete ring of Cartilage around the The arytenoid Cartilages are a pair of small three-sided Pyramids which form part of the Larynx, to which the Vocal cords are attached The corniculate cartilages ( cartilages of Santorini) are two small conical nodules consisting of yellow elastic Cartilage, which articulate with the summits of the The cuneiform cartilages of the Larynx (cartilages of Wrisberg) are two small elongated pieces of yellow elastic Cartilage, placed one on either side

Images

Bronchi, bronchial tree, and lungs	Larynx	The cartilages of the larynx. Posterior view.	The ligaments of the larynx. Antero-lateral view.
Sagittal section of the larynx and upper part of the trachea.	Coronal section of larynx and upper part of trachea.	The entrance to the larynx, viewed from behind.	Laryngoscopic view of interior of larynx.
Sagittal section of nose mouth, pharynx, and larynx.	Endoscopic image of larynx seen at the time of intubation of the esophagus during gastroscopy. The esophagus or oesophagus (see American and British English spelling differences) sometimes known as the gullet, is an organ in

See also

• Laryngitis
• Epiglottitis
• Intubation
• Phonation
• Voice organ
• Phonetics
• Vocology
• Acoustic phonetics

References

Speech and Hearing Science: Anatomy and Physiology 3rd edition. Willard R. Zemlin. 1988. Prentice-Hall, Inc. Englewood Cliffs, New Jersey. ISBN 0-13-827429-0

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic