The larynx is situated within the anterior facet of the neck, anterior come the inferior part of the pharynx and superior to the trachea. That is primary role is to defend the lower airway by closeup of the door abruptly upon mechanically stimulation, thereby halting respiration and also preventing the entry of foreign matter right into the airway. Other functions of the larynx encompass the production of sound (phonation), coughing, the Valsalva maneuver, and control of ventilation, and acting as a sensory organ.

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The larynx is created of 3 large, unpaired cartilages (cricoid, thyroid, epiglottis); 3 pairs of smaller cartilages (arytenoids, corniculate, cuneiform); and also a number of intrinsic muscles (see the image and also videobelow). The hyoid bone, while technically not part of the larynx, offers muscular attachments from above that assist in laryngeal motion. <1, 2, 3, 4, 5>


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Larynx anatomy.
This video is of one esophagoscopy on a 3 year old child. The esophagoscope is introduced through the mouth. As the limit enters the esophageal inlet, you deserve to see the larynx v an endotracheal tube passing v the vocal folds. Video clip courtesy the Ravindhra G Elluru, MD, PhD.

The cricoid cartilage is a ring of hyaline cartilage located at the inferior aspect of the larynx and is the only complete ring the cartilage around the trachea. It has actually the form of a "signet ring," through a broad section posterior to the airway (lamina of cricoid cartilage) and also a narrower section circling anteriorly (arch the cricoid cartilage). The posterior surface of the lamina includes 2 oval depressions, which serve as attachments sites for the posterior cricoarytenoid muscles, be separate by a upright midline ridge the serves as an attachment to the esophagus.

At the junction that the lamina v the arch, small, ring articular facets exist top top the external posterolateral surface of each side the the ring the articulate through the worse horn that the thyroid cartilage. The reduced border that the cricoid cartilage is associated to the very first tracheal ring by the cricotracheal ligament. The upper border of the cricoid cartilage gives attachment come the cricothyroid ligament on the anterior midline, the cricothyroid muscle on the lateral aspects, and the bases the a pair of arytenoid cartilages on both sides of the posterior aspect.


The thyroid cartilage is the largest of the laryngeal cartilages. The is formed by a right and also a left lamina that space separated posteriorly and joined with each other at an acute angle in the anterior midline, developing the laryngeal prominence, generally known together the Adam’s apple. The laryngeal prominence is more apparent in men, since the angle between the 2 laminae is more acute in guys (90°) than in women (120°).

The superior thyroid notch is a V-shaped notch immediately over the laryngeal prominence, when the inferior thyroid notch is much less distinct and located in the midline along the basic of the cartilage (see the picture below). The 2 laminae space quadrilateral in shape and type the lateral surface of the thyroid cartilage that prolong obliquely to cover each side of the trachea.


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Larynx anatomy.

The posterior aspect of every lamina is elongated to form a exceptional horn and inferior horn. The medial surfaces of the worse horns articulate v the external posterolateral surface of the cricoid cartilage. The inferior border the the thyroid cartilage is attached come the cricoid cartilage by the cricothyroid membrane in the midline and also the cricothyroid muscles on either side. The premium horn along with the whole superior edge of the thyroid cartilage is attached to the hyoid bone through the thyrohyoid membrane.


The epiglottis is a leaf-shaped cartilage the moves down to kind a lid end the glottis and protect the larynx indigenous aspiration of foods or liquids gift swallowed. That is enclosed by that is stem to the midline the the inner element of the thyroid cartilage, about halfway between the edge of the laryngeal prominence and also the inferior notch.


It is attached via the thyroepiglottic ligament and projects posterosuperiorly to cover the superior opening of the larynx. The midline the the superior surface that the epiglottis is likewise attached to the body of the hyoid bone via the hyoepiglottic ligament. The mucous membrane spanning the top anterior component of the epiglottis mirrors off the sides of the epiglottis, offering rise to the glossoepiglottic folds. The aryepiglottic folds are mucosal folds on the posterior surface ar of the epiglottis. The depressions top top either next of the mean fold, between the source of the tongue and the epiglottis, are called the valleculae epiglottica.


The arytenoid cartilages kind the part of the larynx to which the vocal ligaments and also vocal wrinkle attach. They space pyramidal in shape and also have 3 surfaces, a base, and an apex. Lock are located superior come the cricoid cartilage in the posterior part of the larynx, with the basic of the arytenoid cartilages articulating on one of two people side with the posterior aspect of the upper border of the cricoid lamina. The anterior edge of the base of the arytenoid cartilage is elongated to type a vocal process for attachments of the vocal ligament, when the lateral angle is elongated to form a muscular procedure for attachments of the posterior and lateral cricoarytenoid muscles.


The posterior surface ar of the arytenoid cartilage provides attachment come the arytenoid muscle. The anterolateral surface has actually 2 depressions because that attachment come the false vocal cord (vestibular ligament) and also the vocalis muscle. The medial surface has actually a mucosal lining that creates the lateral element of the respiratory component of the glottis. The apex that the arytenoid cartilage is pointed and articulates with the corniculate cartilage.


The corniculate cartilages room 2 small, conical cartilages that articulate with the apices the the arytenoid cartilages, offer to extend them posteriorly and medially. They are located in the posterior components of the aryepiglottic wrinkle of mucous membrane.


The cuneiform cartilages space 2 small, club-shaped cartilages that lie anterior to the corniculate cartilages in the aryepiglottic folds. They kind small, whitish elevations top top the surface of the mucous membrane simply anterior the the arytenoid cartilages.


The thyrohyoid membrane is a large fibroelastic ligament the spans in between the superior border the the thyroid cartilage and the hyoid bone above. It has an aperture ~ above the lateral surface of every side because that the remarkable laryngeal arteries, nerves, and also lymphatics.


The hyoepiglottic ligament extends native the midline the the superior surface that the epiglottis to the human body of the hyoid bone, located anterosuperiorly. The cricotracheal ligament associate the lower border the the cricoid cartilage come the upper border that the an initial tracheal cartilage ring.


The conus elasticus, a submucosal membrane, expand superiorly from the anterior arch that the cricoid cartilage and also attaches come the thyroid cartilage anteriorly and the vocal processes of the arytenoid cartilages posteriorly. The complimentary superior margin that the conus elasticus is thickened to kind the vocal ligament, which creates the vocal wrinkle (true vocal cords) once covered by mucosa.


The quadrangular membrane, one more submucosal sheet, extends between the lateral aspects of the epiglottis and the anterolateral surface ar of the arytenoid cartilages on every side. The totally free lower inferior margin the this membrane is thickened to kind the vestibular ligament, which develops the vestibular folds (false vocal cords) when covered by mucosa.


The laryngeal central cavity is tubular in shape and also lined with mucosa. The superior facet of the cavity (laryngeal inlet) opens right into the pharynx, inferior and also posterior come the tongue. The inferior facet of the cavity is constant with the lumen the the trachea.


The laryngeal cavity may be split into 3 major regions: the vestibule, the middle, and the infraglottic space. The vestibule is the upper part of the cavity, in between the laryngeal inlet and the vestibular folds. The middle section of the cavity, or the voice box, is created by the vestibular folds over and the vocal wrinkle below. The infraglottic an are is the lower section of the cavity, in between the vocal folds and also inferior opening of the larynx into the trachea.


On either side of the center laryngeal cavity, in between the vestibular and also vocal folds, the mucosa bulges laterally to form troughs known as the laryngeal ventricles. The laryngeal saccules are tubular extensions of each ventricle anterosuperiorly in between the vestibular fold and also the thyroid cartilage. The is assumed that the wall surfaces of these saccules contain countless mucous glands that lubricate the vocal folds.


The rima vestibuli is the triangular-shaped opening between the 2 adjacent vestibular folds. The apex lies anterior and also the base is created by the posterior wall of the laryngeal cavity. The rima glottidis is a narrower, triangular-shaped opened that lies beneath the rima vestibuli, created by the 2 adjacent vocal folds.


The piriform recesses (piriform sinuses) are present on either side of the anterolateral wall of the laryngopharynx. They space bounded medially by the aryepiglottic folds and also laterally by the thyroid cartilage and also thyrohyoid membrane. They space a typical place for food to end up being trapped.


The cricothyroid muscles room attached come the anterolateral surfaces of the arch of the cricoid cartilage and also expand superiorly and also posteriorly to affix to the worse border the the thyroid cartilage. They are the only laryngeal muscles provided by the exterior branch the the exceptional laryngeal nerve, a branch of vagus nerve (cranial nerve X) listed below the base of the skull.


These muscles duty to elevate the anterior arch that the cricoid cartilage and depress the posterior portion of the thyroid cartilage lamina. This to produce tension and elongation of the vocal cords, causing higher-pitch phonation.


The posterior cricoarytenoid muscles prolong from the oval depressions on the posterior surface of the cricoid lamina on each side and extend increase to the muscular process of the arytenoid cartilage top top the very same side. These muscles role to turn the arytenoid cartilages laterally, in order to abducting the vocal cords. Their action opposes the of the lateral cricoarytenoid muscles. The posterior cricoarytenoid muscles receive innervation native the recurrent laryngeal branch the the vagus nerve (CN X).


The lateral cricoarytenoid muscle on each side extends indigenous the top border that the arch of the cricoid cartilage come the muscular procedure of the arytenoid cartilage ~ above the very same side. This muscles duty to turn the arytenoid cartilages medially, thereby adducting the vocal cords. The lateral cricoarytenoid muscles obtain innervation indigenous the recurrent laryngeal branch the the vagus nerve (CN X).


The transverse arytenoid muscle is a single muscle that extends in between the posterior surfaces of each arytenoid cartilage. That main duty is adduction that the vocal cords, and also it is innervated through both recurrent laryngeal branches that the vagus nerves (CN X).


The thyroarytenoid muscles operation from a vertical line on the interior surface that the thyroid cartilage edge and adjacent to the outside surface that the cricothyroid ligament to the anterolateral surface ar of the arytenoid cartilage. Every muscle consists of 2 parts: the vocalis and also thyroepiglottic part.


The vocalis part lies deep and also inferior, parallel with the vocal ligament to which the is attached at the posterior end. The thyroepiglottic part is occasionally defined as a separate muscle; the lies superior and continues right into the aryepiglottic fold, wherein some fibers extend to the margin that the epiglottis. These muscles role to draw the arytenoid cartilages forward, in order to relaxing and also shortening the vocal cords, while additionally rotating the arytenoid cartilages inward, therefore adducting the vocal folds and narrowing the rima glottis. The thyroarytenoid muscles obtain innervation indigenous the recurrent laryngeal branch of the vagus nerve (CN X).


The exceptional laryngeal nerves arise indigenous the worse ganglia that the vagus nerve and also receive a branch native the exceptional cervical forgiveness ganglion on every side in the upper neck. Castle descend surrounding to the pharynx on either side, behind the inner carotid artery, and also divide into internal and also external branches.


The outside branch (external laryngeal nerve) descends beneath the sternothyroid muscle and supplies the cricothyroid muscle. Injury to this nerve during thyroidectomy or cricothyrotomy causes hoarseness the the voice and also an inability to develop high-pitched sounds.


The internal branch (internal laryngeal nerve) pierces the thyrohyoid membrane and also supplies sensory innervation come the laryngeal cavity under to the level of the vocal folds. The is responsible for the cough reflex.


The recurrent laryngeal branches that the vagus nerves ascend right into the larynx in ~ the groove in between the esophagus and the trachea. The left recurrent laryngeal nerve originates in the thorax, looping under the aortic arch before ascending, when the appropriate recurrent laryngeal nerve originates in the neck.


These nerves space responsible for providing sensory innervation to the laryngeal cavity listed below the level the the vocal folds, as well as motor innervation to every laryngeal muscles except the cricothyroid. Since the nerves run instantly posterior to the thyroid gland, they are at risk of injury during thyroidectomies. Unilateral nerve damage presents through voice changes, including hoarseness. Bilateral nerve damages may result in aphonia (inability to speak) and also breathing difficulties.


The superior and also inferior laryngeal arteries supply the bulk of blood come the larynx. The exceptional laryngeal artery originates from the exceptional thyroid branch that the exterior carotid artery and enters the larynx with the internal branch that the exceptional laryngeal nerve v the lateral aperture the the thyrohyoid membrane. The inferior laryngeal artery originates indigenous the worse thyroid branch of the thyrocervical trunk, i beg your pardon is a branch the the subclavian artery. That ascends right into the larynx within the groove between the esophagus and the trachea, along with the recurrent laryngeal branch the the vagus nerve (CN X).


The superior and inferior laryngeal veins drainpipe the larynx and share the exact same course together the arteries. The remarkable laryngeal veins drainpipe into the exceptional thyroid veins, i m sorry empty right into the internal jugular veins. The inferior laryngeal veins drainpipe into the inferior thyroid veins, which both empty right into the left brachiocephalic vein.


The lymphatic vessels that drain above the vocal folds take trip along the superior laryngeal artery and drain to the deep cervical lymph nodes in ~ the bifurcation the the common carotid artery. The lymphatic vessels that drain below the vocal folds travel along the worse thyroid artery and also drain come the upper tracheal lymph nodes.



Swallowing

During swallowing, the rima glottidis, rima vestibuli, and also vestibule room closed. The backward motion of the tongue forces the epiglottis end the opening of the glottis to cover the laryngeal inlet and also prevent aspiration that swallowed material into the lungs. The larynx additionally moves upward and forward, which help to open up the esophagus because that the passage of the swallowed material.


Respiration

During respiration, the rima glottidis, rima vestibuli, and also vestibule space open. The vocal folds might be further abducted during forced inspiration, by the activity of the posterior cricoarytenoid muscles, for this reason widening the rima glottidis and increasing the diameter of the laryngeal airway.

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Phonation

During phonation, the vocal cords and also arytenoid cartilages room adducted. When air is required through the closed rima glottidis, the vocal cords vibrate against one one more to produce sounds.



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Laryngeal Tissue


The lumen that the larynx is lined mainly with respiratory tract epithelium, consists of ciliated, pseudostratified columnar epithelium with a rich population of goblet cells, and also a submucosa containing combined mucous and also serous glands. The epiglottis is inside wall by a comparable respiratory epithelium top top its laryngeal surface; however, its lingual surface is lined with stratified squamous epithelium. The vestibular folds and vocal folds are also lined v a special stratified squamous epithelium, which features to protect the mucosa from abrasion caused by the rapid activity of air when breathing and also during phonation. (See the photo below.)