HOME

TheInfoList




The larynx (), commonly called the voice box, is an
organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly cate ...
in the top of the
neck The neck is the part of the body on many vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With f ...

neck
involved in breathing, producing sound and protecting the
trachea The trachea, also known as the windpipe, is a tube that connects the to the bronchi of the s, allowing the passage of , and so is present in almost all air- s with lungs. The trachea extends from the larynx and branches into the two primary . ...

trachea
against food aspiration. The opening of larynx into
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...

pharynx
known as the laryngeal inlet is about 4–5 centimeters in
diameter In geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space ...

diameter
. The larynx houses the
vocal cords In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and ...
, and manipulates
pitch Pitch may refer to: Acoustic frequency * Pitch (music), the perceived frequency of sound including "definite pitch" and "indefinite pitch" ** Absolute pitch or "perfect pitch" ** Pitch class, a set of all pitches that are a whole number of octaves ...
and
volume Volume is a scalar quantity expressing the amount Quantity or amount is a property that can exist as a multitude Multitude is a term for a group of people who cannot be classed under any other distinct category, except for their shared fact ...
, which is essential for
phonation The term phonation has slightly different meanings depending on the subfield of phonetics Phonetics is a branch of that studies how humans produce and perceive sounds, or in the case of s, the equivalent aspects of sign. Phoneticians—lingu ...
. It is situated just below where the tract of the
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...

pharynx
splits into the trachea and the
esophagus The esophagus (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American E ...

esophagus
. The word larynx (plural larynges) comes from a similar
Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the diale ...
word (λάρυγξ ''lárynx'').


Structure

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 ciliated columnar epithelium except for the vocal folds. The cavity of the larynx extends from its triangle-shaped
inlet An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of water, body of salt water, such as a Sound (geography), sound, bay, lagoon, or marsh. Overview In sea coasts, ...
, to the
epiglottis The epiglottis is a leaf-shaped flap in the throat In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the Human pharynx, pharynx and larynx. An important section of it is the epiglo ...

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 folds The vestibular fold (ventricular fold, superior or false vocal cord) is one of two thick folds of mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body and covers the surface of internal organs. It co ...
. They are also sometimes called the false vocal cords for the rather obvious reason that they play no part in vocalization. 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 Standard anatomical terms of location deal unambiguously with the anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology, an organism (from Ancient ...
neck at the level of the
cervical vertebrae In tetrapod Tetrapods (; from Greek 'four' and 'foot') are four-limbed animals constituting the superclass Tetrapoda . It includes extant and extinct amphibians, reptiles (including dinosaurs and therefore birds), and synapsids (including ...

cervical vertebrae
C3–C6. It connects the inferior part of the
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...

pharynx
(hypopharynx) with the
trachea The trachea, also known as the windpipe, is a tube that connects the to the bronchi of the s, allowing the passage of , and so is present in almost all air- s with lungs. The trachea extends from the larynx and branches into the two primary . ...

trachea
. The laryngeal
skeleton A skeleton is a structural frame that supports an animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consu ...

skeleton
consists of nine
cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic is a word often used to describe or identify certain types of elastomer An elastomer is a polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-m ...

cartilage
s: three single ( epiglottic,
thyroid The thyroid, or thyroid gland, is an endocrine gland Endocrine glands are ductless glands of the endocrine system The endocrine system is a messenger system comprising feedback loops of the hormones released by internal glands of an organi ...

thyroid
and
cricoid The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the Vertebrate trachea, trachea. It forms the back part of the larynx, voice box and funct ...
) and three paired (
arytenoid
arytenoid
, corniculate, and
cuneiform Cuneiform is a Logogram, logo-Syllabary, syllabic writing system, script that was used to write several languages of the Ancient Near East. The script was in active use from the early Bronze Age until the beginning of the Common Era. It is nam ...
). The
hyoid bone The hyoid bone (lingual bone or tongue-bone) () is a horseshoe A horseshoe is a fabricated product, normally made of metal A metal (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ε ...
is not part of the larynx, though the larynx is suspended from the hyoid. The larynx extends vertically from the tip of the
epiglottis The epiglottis is a leaf-shaped flap in the throat In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the Human pharynx, pharynx and larynx. An important section of it is the epiglo ...

epiglottis
to the inferior border of the
cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the Vertebrate trachea, trachea. It forms the back part of the larynx, voice box and func ...
. Its interior can be divided in supraglottis,
glottis The glottis is the opening between the vocal folds In humans, vocal cords, also known as vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through vocalization. The size of vocal cords affects the ...
and
subglottis The subglottis or subglottic region is the lower portion of the larynx, extending from just beneath the vocal cords down to the top of the Vertebrate trachea, trachea.
.


Cartilages

There are nine cartilages, three unpaired and three paired (3 pairs=6), that support the mammalian larynx and form its skeleton. Unpaired cartilages: *
Thyroid cartilage The thyroid cartilage is the largest of the nine cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic fibers (or yellow fibers) are an essential component of the extracellular matrix In biology Biol ...

Thyroid cartilage
: This forms the
Adam's apple The Adam's apple or laryngeal prominence, is the lump or protrusion in the human neck The neck is the part of the body on many vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular ...
(also called the laryngeal prominence). It is usually larger in males than in females. The
thyrohyoid membrane The thyrohyoid membrane (or hyothyroid membrane) is a broad, fibro-elastic sheet of the larynx The larynx (), commonly called the voice box, is an organ in the top of the neck The neck is the part of the body on many vertebrate Vertebrates ( ...
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 The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the Vertebrate trachea, trachea. It forms the back part of the larynx, voice box and func ...
: 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 The epiglottis is a leaf-shaped flap in the throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebra, vertebrae. It contains the Human pharynx, pharynx and larynx. An important secti ...

Epiglottis
: A large, spoon-shaped piece of elastic cartilage. During
swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of ...
, 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 The arytenoid () cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic is a word often used to describe or identify certain types of elastomer An elastomer is a polymer A polymer (; Greek ''wikt:poly- ...

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 In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and ...
. These are triangular pieces of mostly hyaline cartilage located at the posterosuperior border of the cricoid cartilage. *
Corniculate cartilages The corniculate cartilages (cartilages of Santorini) are two small conical nodules consisting of elastic cartilage, which articulate with the summits of the arytenoid cartilages and serve to prolong them posteriorly and medially. They are situate ...
: Horn-shaped pieces of elastic cartilage located at the apex of each arytenoid cartilage. *
Cuneiform cartilages In the human larynx, the cuneiform cartilages (from Latin: ''cunei'', "wedge-shaped"; also known as cartilages of Wrisberg) are two small, elongated pieces of yellow elastic cartilage, placed one on either side, in the aryepiglottic fold. The cu ...
: 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. The intrinsic muscles are divided into respiratory and the phonatory muscles (the muscles of
phonation The term phonation has slightly different meanings depending on the subfield of phonetics Phonetics is a branch of that studies how humans produce and perceive sounds, or in the case of s, the equivalent aspects of sign. Phoneticians—lingu ...
). The respiratory muscles move the
vocal cord In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and ...
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 The posterior cricoarytenoid muscles are small, paired intrinsic muscles of the larynx that extend between cricoid cartilage to the arytenoid cartilage The arytenoid () cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic ...
s. The phonatory muscles are divided into adductors (
lateral cricoarytenoid muscle The lateral cricoarytenoid (also anterior cricoarytenoid) muscles extend from the lateral cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of ...
s,
arytenoid muscle The arytenoid is a single muscle, filling up the posterior concave surfaces of the arytenoid cartilages. It arises from the posterior surface and lateral border of one arytenoid cartilage The arytenoid () cartilage Cartilage (cartilaginous tiss ...
s) and tensors (
cricothyroid muscle The cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation. It is innervated by the superior laryngeal nerve. Its action tilts the thyroid forward to help tense the vocal cords. Structure The cricothyroid muscle att ...
s,
thyroarytenoid muscle The thyroarytenoid muscle is a broad, thin muscle that forms the body of the vocal fold In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through v ...
s).


Intrinsic

The intrinsic laryngeal muscles are responsible for controlling sound production. *
Cricothyroid muscle The cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation. It is innervated by the superior laryngeal nerve. Its action tilts the thyroid forward to help tense the vocal cords. Structure The cricothyroid muscle att ...
lengthen and tense the vocal cords. *
Posterior cricoarytenoid muscle The posterior cricoarytenoid muscles are small, paired intrinsic muscles of the larynx that extend between cricoid cartilage to the arytenoid cartilage The arytenoid () cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic ...
s abduct and externally rotate the arytenoid cartilages, resulting in abducted vocal cords. *
Lateral cricoarytenoid muscle The lateral cricoarytenoid (also anterior cricoarytenoid) muscles extend from the lateral cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of ...
s adduct and internally rotate the arytenoid cartilages, increase medial compression. * Transverse arytenoid muscle adduct the arytenoid cartilages, resulting in adducted vocal cords. *
Oblique arytenoid muscle The oblique arytenoid, the more superficial Arytenoid muscle, forms two Muscle fascicle, fasciculi, which pass from the base of one cartilage to the apex of the opposite one, and therefore cross each other like the limbs of the letter X; a few fiber ...
s narrow the laryngeal inlet by constricting the distance between the arytenoid cartilages. *
Thyroarytenoid muscle The thyroarytenoid muscle is a broad, thin muscle that forms the body of the vocal fold In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through v ...
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 Ca2+-buffering profile that predicts their better ability to handle calcium changes in comparison to other muscles. 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 Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy that primarily affects boys. Muscle weakness usually begins around the age of four, and worsens quickly. Muscle loss typically occurs first in the thighs and pelvis Th ...
. Furthermore, different levels of Orai1 in rat intrinsic laryngeal muscles and
extraocular muscle The extraocular muscles are the six muscle Muscle is a soft tissue found in most animals. Muscle cells contain protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residue ...
s 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. rachea. *
Sternothyroid muscle The sternothyroid muscle, or sternothyroideus, is an infrahyoid muscle in the neck. It acts to depress the hyoid bone. It is below the sternohyoid muscle. It is shorter and wider than the sternohyoid. Structure The sternothyroid arises from t ...
s depress the larynx. (Innervated by ansa cervicalis) *
Omohyoid muscle The omohyoid muscle is a muscle that depresses the hyoid. It is located in the front of the neck, and consists of two bellies separated by an intermediate tendon. The omohyoid muscle is proximally attached to the scapula and distally attached to t ...

Omohyoid muscle
s depress the larynx. (Ansa cervicalis) *
Sternohyoid muscle The sternohyoid muscle is a thin, narrow muscle attaching the hyoid bone The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate sk ...
s depress the larynx. (Ansa cervicalis) * Inferior constrictor muscles. (CN X) *
Thyrohyoid muscle The thyrohyoid muscle is a small skeletal muscle Skeletal muscle (also called striated muscle - although cardiac muscle is also striated) is one of three major muscle types, the others being cardiac muscle and smooth muscle. It is a form of striat ...
s elevates the larynx. (C1) *
Digastric The digastric muscle (also digastricus) (named ''digastric'' as it has two 'bellies') is a small muscle Muscle is a soft tissue found in most animals. Muscle cells contain protein Proteins are large biomolecules or macromolecules that a ...
elevates the larynx. (CN V3, CN VII) *
Stylohyoid The stylohyoid muscle is a Gracility, slender muscle, lying anterior and Anatomical terms of location#Superior and inferior, superior of the posterior belly of the digastric muscle. It is one of the suprahyoid muscles. It shares this muscle's inne ...
elevates the larynx. (CN VII) * Mylohyoid elevates the larynx. (CN V3) *
Geniohyoid The geniohyoid muscle is a narrow muscle situated superior to the medial border of the mylohyoid muscle. It is named for its passage from the chin ("genio-" is a standard prefix for "chin") to the hyoid bone. Structure It arises from the inferior ...
elevates the larynx. (C1) *
Hyoglossus The hyoglossus, thin and quadrilateral, arises from the side of the body and from the whole length of the greater cornu The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between t ...

Hyoglossus
elevates the larynx. (CN XII) *
Genioglossus The genioglossus is one of the paired extrinsic muscles of the tongue. The genioglossus is the major muscle responsible for protruding (or sticking out) the tongue. Structure Genioglossus is the fan-shaped extrinsic tongue muscle that forms the maj ...

Genioglossus
elevates the larynx. (CN XII)


Nerve supply

The larynx is
innervate A nerve is an enclosed, cable-like bundle of fibers (called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, ...
d by branches of the
vagus nerve The vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axi ...
on each side. Sensory innervation to the glottis and laryngeal vestibule is by the internal branch of the
superior laryngeal nerve The superior laryngeal nerve is a branch of the vagus nerve The vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with the parasympathetic control of the heart The heart is a m ...
. The external branch of the superior laryngeal nerve innervates the
cricothyroid muscle The cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation. It is innervated by the superior laryngeal nerve. Its action tilts the thyroid forward to help tense the vocal cords. Structure The cricothyroid muscle att ...
. Motor innervation to all other muscles of the larynx and sensory innervation to the subglottis is by the
recurrent laryngeal nerve The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies all the Larynx#Intrinsic, intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerv ...

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 laryngeal nerve causes weakened phonation because the vocal cords cannot be tightened. Injury to one of the recurrent laryngeal nerves produces
hoarseness A hoarse voice, also known as dysphonia or hoarseness, is when the voice involuntarily sounds breathy, raspy, or strained, or is softer in volume or lower in pitch. A hoarse voice, can be associated with a feeling of unease or scratchiness in the t ...
, 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. The larynx descends as the child grows.


Function


Sound generation

Sound is generated in the larynx, and that is where
pitch Pitch may refer to: Acoustic frequency * Pitch (music), the perceived frequency of sound including "definite pitch" and "indefinite pitch" ** Absolute pitch or "perfect pitch" ** Pitch class, a set of all pitches that are a whole number of octaves ...
and
volume Volume is a scalar quantity expressing the amount Quantity or amount is a property that can exist as a multitude Multitude is a term for a group of people who cannot be classed under any other distinct category, except for their shared fact ...
are manipulated. The strength of
expiration Expiration or expiration date may refer to: Expiration Expiration may refer to: *Death *Exhalation of breath, breathing out *Expiration (options), the legal termination of an option to take an action *Shelf life, or the time after which a product ...
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 The vocal tract is the cavity in human bodies and in animals where the sound produced at the sound source (larynx in mammals; syrinx (biology), syrinx in birds) is filtered. In birds it consists of the Vertebrate trachea, trachea, the Syrinx (bio ...
, configured differently based on the position of the
tongue The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...

tongue
,
lip Lips are a visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be an ...

lip
s,
mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization ...

mouth
, and
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...

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 term phonation has slightly different meanings depending on the subfield of phonetics Phonetics is a branch of that studies how humans produce and perceive sounds, or in the case of s, the equivalent aspects of sign. Phoneticians—lingu ...
). 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 The thyroid cartilage is the largest of the nine cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic fibers (or yellow fibers) are an essential component of the extracellular matrix In biology Biol ...

thyroid cartilage
forward and backward on the
cricoid cartilage The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the Vertebrate trachea, trachea. It forms the back part of the larynx, voice box and func ...
(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 The term phonation has slightly different meanings depending on the subfield of phonetics Phonetics is a branch of that studies how humans produce and perceive sounds, or in the case of s, the equivalent aspects of sign. Phoneticians—lingu ...
to rise or fall. In most males the vocal cords are longer and with a greater mass than most females' vocal cords, producing a lower pitch. The vocal apparatus consists of two pairs of folds, the
vestibular folds The vestibular fold (ventricular fold, superior or false vocal cord) is one of two thick folds of mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body and covers the surface of internal organs. It co ...
(false vocal cords) and the true
vocal cords In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and ...
. The vestibular folds are covered by
respiratory epithelium The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex biological network, network which connects several biologically relevant entities. Biological organization spans sev ...
, while the vocal cords are covered by
stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cell Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

stratified squamous epithelium
. The vestibular folds are not responsible for sound production, but rather for resonance. The exceptions to this are found in
Tibetan chanting
Tibetan chanting
and Kargyraa, a style of
Tuvan throat singing Tuvan throat singing, the main technique of which is known as ''khoomei'' ( tyv, хөөмей, xöömej, mn, хөөмий, khöömii, russian: хоомей, ), includes a type of overtone singing practiced by people in Tuva, Mongolia, and Siberi ...
. 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

The most important role of the larynx is its protecting function; the prevention of foreign objects from entering the lungs by
coughing A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes A microorganism, or microbe,, ''mikros'', "small") and ''organism In biolog ...
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. Another important role of the larynx is abdominal fixation, a kind of
Valsalva maneuver The Valsalva maneuver is performed by moderately forceful attempted exhalation Exhalation (or expiration) is the flow of the breath upright=1.4, X-ray video of a female American alligator while breathing. Breathing (or ventilation) is ...

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 The term phonation has slightly different meanings depending on the subfield of phonetics Phonetics is a branch of that studies how humans produce and perceive sounds, or in the case of s, the equivalent aspects of sign. Phoneticians—lingu ...
. Abduction of the vocal cords is important during physical exertion. The vocal cords are separated by about during normal respiration, but this width is doubled during forced respiration. During
swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth In animal anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of ...
, 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 The lungs are the primary organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma ...

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 A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, ...
reflex In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...

reflex
to protect the lungs. In addition, intrinsic laryngeal muscles are spared from some muscle wasting disorders, such as
Duchenne muscular dystrophy Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy that primarily affects boys. Muscle weakness usually begins around the age of four, and worsens quickly. Muscle loss typically occurs first in the thighs and pelvis Th ...
, 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


Clinical significance


Disorders

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. It is caused by the common cold or by excessive shouting. It is not serious.
Chronic 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 dysphagia, trouble swallowing. Typically, these last under two weeks. Laryngitis is cat ...
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 colds is found on laryngoscopy. *
Ulcers An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing ou ...

Ulcers
may be caused by the prolonged presence of an
endotracheal tube A tracheal tube is a catheter that is inserted into the Vertebrate trachea, trachea for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate Gas exchange, exchange of oxygen and carbon dioxide. Many differ ...

endotracheal tube
. *
Polyps A polyp in zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolu ...
and
vocal cord nodule Vocal cord nodules are bilaterally symmetrical benign {{Unreferenced, date=June 2019, bot=noref (GreenC bot) Benignity (from Latin ''benignus'' "kind, good", itself deriving from ''bonus'' "good" and ''genus'' "origin") is any condition that is h ...
s are small bumps caused by prolonged exposure to
tobacco smoke Tobacco smoke is a soot, sooty aerosol produced by the incomplete combustion of tobacco during the tobacco smoking, smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to a ...
and vocal misuse, respectively. * Two related types of cancer of the larynx, namely
squamous cell carcinoma Squamous cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that result from Epithelium#Cell types, squamous cells. These cells form on the surface of the skin, on the lining of hollow organ ...

squamous cell carcinoma
and
verrucous carcinoma Verrucous carcinoma (VC) is an uncommon variant of squamous cell carcinoma. This form of cancer is often seen in those who chew tobacco or use Snuff (tobacco), snuff orally, so much so that it is sometimes referred to as "Snuff dipper's cancer". ...
, are strongly associated with repeated exposure to cigarette smoke and alcohol. *
Vocal cord paresis Vocal cord paresis, also known as recurrent laryngeal nerve paralysis or vocal fold paralysis, is an injury to one or both recurrent laryngeal nerve The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that sup ...
is weakness of one or both vocal cords that can greatly impact daily life. * Idiopathic laryngeal spasm. *
Laryngopharyngeal reflux Laryngopharyngeal reflux (LPR) 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 a ...
is a condition in which acid from the stomach irritates and burns the larynx. Similar damage can occur with
gastroesophageal reflux disease Gastroesophageal reflux disease (GERD), is a chronic condition in which stomach contents rise up into the esophagus The esophagus (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States E ...
(GERD). * 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 The perichondrium (from Greek language, Greek el, περί, peri, around, label=none and el, χόνδρος, chondros, cartilage, label=none) is a layer of dense irregular connective tissue that surrounds the cartilage of developing bone. It consi ...
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 (physiology), respiration. In mild cases it can lead to exaggerated or "raspy" breathing or Thermoregulation, panting, and in serious cases can pose a considerable need for treatment. *
Duchenne muscular dystrophy Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy that primarily affects boys. Muscle weakness usually begins around the age of four, and worsens quickly. Muscle loss typically occurs first in the thighs and pelvis Th ...
, 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. 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.


Treatments

Patients who have lost the use of their larynx are typically prescribed the use of an electrolarynx device. Larynx Organ transplant, transplants are a rare procedure. The world's first successful operation took place in 1998 at the Cleveland Clinic, and the second took place in October 2010 at the University of California Davis Medical Center in Sacramento.


Other animals

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. 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.


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 The epiglottis is a leaf-shaped flap in the throat In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the Human pharynx, pharynx and larynx. An important section of it is the epiglo ...

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. 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 (biology), syrinx.


History

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


Additional images

File:Slide14rom.JPG, Larynx. Deep dissection. Anterior view. File:Slide36uru.JPG, Larynx. Deep dissection. Posterior view.


See also

* Articulatory phonetics * Electrolarynx * Histology of the vocal cords * Origin of speech


References


Notes


Sources

* * * * * * * * {{Authority control Larynx, Human head and neck Human voice Phonetics Human throat Respiratory system Speech organs