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Larynx

 
Last reviewed by: Aleksey Portnov , medical expert, on 31.05.2018
 

The larynx performs respiratory and voice-forming functions, it protects the lower respiratory tract from the ingress of foreign particles into them. The larynx resembles an irregularly shaped tube, widened at the top and narrowed at the bottom. The upper boundary of the larynx is at the level of the lower edge of the IV cervical vertebra; lower - at the lower edge of the sixth cervical vertebra. The larynx is located in the anterior region of the neck, its relationships with neighboring organs are complex. At the top of the larynx is attached to the hyoid bone, below - it extends into the trachea. The front of the larynx is covered with superficial and pre-tracheal plates of the cervical fascia and the sub-lingual muscles of the neck. Front and sides of the larynx is covered by the right and left lobes of the thyroid gland. Behind the larynx is the guttural part of the pharynx. The close connection between the larynx and the pharynx is explained by the development of the respiratory system (epithelium and glands) from the central wall of the pharyngeal part of the primary intestine and the accessory of the pharynx simultaneously to the respiratory and digestive tracts. At the level of the oropharynx, there is a cross between the respiratory and digestive tracts.

Departments of the larynx. In the larynx, anterior vestibule, interventricular department and podogolovoy cavity are distinguished.

The threshold of the larynx (vestibulum laryngis) lies between the entrance to the larynx at the top and the folds of the vestibule (false vocal folds) at the bottom. Between the folds of the vestibular (plicae vestibulares) there is a crevice aperture (rima vestibuli). The anterior wall of the vestibule (4 cm in height) is formed by an epiglottis covered with a mucous membrane, behind - with arytenoid cartilages. The height of this posterior wall of the vestibule of the larynx is 1.0-1.5 cm. The lateral walls of the vestibule are formed on each side by a tarsal-armaged ligament.

The interventricular department, the shortest, is located between the folds of the vestibule at the top and the vocal folds at the bottom.

On each side there is a depression - the ventriculum laryngis (ventriculum laryngis). The right and left vocal cords (plicae vocales) limit the vocal cleft (rima glottidis). The length of this gap in men is 20-24 mm, in women 16-19 mm. The width of the glottis during respiration is 5 mm on average, increases with voice formation. The large front part of the vocal cicle is called the inter-membranous part (pars intermembranacea).

The cavity cavity (cavitas infraglottica) is the lower larynx, located between the vocal folds from the top and up to the entrance to the trachea at the bottom.

Cartilages of the larynx. The basis of the larynx (skeleton) is the cartilage, connected by ligaments, joints and muscles. Cartilages of the larynx are divided into paired and unpaired. Unpaired cartilage includes thyroid, cricoid cartilage and epiglottis. To the twin cartilages belong the aryps, carobs, wedge-shaped and unstable granular cartilages of the larynx.

Cartilago thyroidea (cartilago thyroidea), the largest cartilage of the larynx, consists of two quadrangular plates connected at an angle in the anterior part of the larynx. The angle of joining the plates in women is about 120 °, in men - 90 °. In men, this angle strongly protrudes forward, forming a protrusion of the larynx (prominentia laryngis) - "Adam's apple". The right and left plates of the thyroid cartilage (lamina dextra et lamina sinistra) diverge backward and laterally, forming a shield-like structure. On the upper edge of the cartilage (above the laryngeal lobe) there is a deep triangular shape of the upper thyroid gland (incisura thyroidea superior). The lower thyroid incision (incisura thyroidea inferior) is weakly expressed, it is located on the lower edge of the cartilage. The posterior margins of the plates on each side form a longer upper horn (cornu superius) and a short lower horn (cornu inferius), which has an articular area for connection to the cricoid cartilage. On the outer surface of both plates of the thyroid cartilage there is a spit line (linea obliqua) - the place of attachment of the sternoid-prominent and thyroid-lingual muscles.

Ring-like cartilage (cartilago cricoidea) resembles a ring. It has a forward arc (arcus cartilaginis cricoideae) and back - a quadrangular wide plate (lamina cartilaginis cricoideae). On the upper lateral margin of the plate of the cricoid cartilage on each side there is an articular surface for articulation with the arytenoid cartilage of the corresponding side. On the lateral part of the plate of the cricoid cartilage, at the point of its transition into the arc, there is a paired articular surface for connection with the lower horn of the thyroid cartilage.

The arytenoid cartilago arytenoidea externally resembles a pyramid with a base pointing downward and upwards - the apex. The base of the arytenoid cartilage (basis cartilaginis arytenoideae) has an articular surface (facies articularis), which participates in the formation of the pericuminally punctate joint. The apex of cartilaginous arytenoideae is pointed and tilted backward. A short vocal ostium (processus vocalis), formed by an elastic cartilage, lies aft from the base of the arytenoid cartilage. A vocal cord is attached to this appendage. Laterally from the base of the arytenoid cartilage a short and thick muscular process (processus muscularis) departs, to which the muscles are attached, which move the arytenoid cartilage. The arytenoid cartilage has an anterolateral surface with a small elongated fossa, a medial and a posterior surface. In the lower part of the anterolateral surface there is a small oblong fovea (fovea oblongata). The medial surface faces the same arytenoid cartilage surface on the opposite side. The transverse and oblique sciatic muscles adhere to the concave posterior surface.

The epiglottis is leaf-shaped, flexible, elastic, and elastic. The epiglottis distinguishes the lower narrow part - the stalk (petiolus epiglottidis) and the wide rounded upper part. The stalk of the epiglottis is attached to the inner surface of the thyroid cartilage, below its upper notch. The epiglottis is located above the entrance to the larynx, covering it in front and from above. The anterior surface of the epiglottis is convex, facing the root of the tongue and the body of the hyoid bone. The concave posterior surface of the epiglottis is directed toward the threshold of the larynx. On this surface are numerous dimples - the mouth of the mucous glands, and the elevation is the epiglottis tuberculum (tuberculum epiglotticum).

Cartilaginous cartilage, cartilago corniculata, elastic, located at the top of the arytenoid cartilage, forms a tubercular tubercle (tuberculum corniculatum) protruding upward.

The sphenoid cartilage, cartilago cartilago cuneiformis, is small in size, is located in the thickness of the scaly belly, higher and anterior to the carpal cartilage. The wedge-shaped cartilage forms a wedge-shaped tuberculum (tuberculum cuneiforme), which forms an elevation (thickening) in this ligament.

Cartilago cartilago triticea is paired, unstable, small in size, located in the thickness of the lateral lining of the thyroid cartilage, stretched between the upper horn of the thyroid cartilage and the end of the great horn of the hyoid bone.

Joints and ligaments of the larynx. Cartilages of the larynx are mobile, which is provided by the presence of two pairs of joints and the muscles acting on them.

The peristonchitis joint (articulatio cricothyroidea) is paired, formed by articulation of the articular surface of the lower horn of the thyroid cartilage and the articular area on the lateral surface of the plate of the cricoid cartilage. This joint is combined, the movements are performed simultaneously in both joints relative to the frontal axis. The thyroid cartilage, when the corresponding muscles contract, leans forward and returns to its original position. When the thyroid cartilage is tilted anteriorly, the distance between its angle and the base of the arytenoid cartilage increases. The corresponding vocal cords are stretched.

Perstnercherchepovidny joint (articulatio cricoarytenoidea) paired, is formed by the articular surfaces of the base of the arytenoid cartilage and the upper-lateral edge of the plate of the cricoid cartilage. In the piercedocutaneous joints, movements occur around the vertical axis. When the arytenoid cartilages rotate inward, their vocal processes converge and the vocal cracks narrows. When turning the arytenoid cartilages outward, the vocal processes diverge to the sides, the vocal chord widens. Possible slight sliding of the arytenoid cartilages relative to the plate of the cricoid cartilage. When the arytenoid cartilages converge, the posterior part of the glottis narrows, widening the cartilage from each other.

In addition to the joints, the cartilages of the larynx are connected with each other, and also with the hyoid bone numerous ligaments.

The hypothaloidal membrane (membrana thyrohyoidea) suspends the larynx to the hyoid bone. This membrane at the bottom is attached to the upper edge of the thyroid cartilage, and above - to the hyoid bone. The hypothaloidal membrane in the middle part thickens and forms the median scutellum ligament (lig.thyrohyoideum medianum). The lateral parts of the lining of the thyrotilagus also form thickenings: the right and left lateral thyrotubby ligaments (lig.thyrohyoideum laterale). The anterior surface of the epiglottis is attached to the hyoid bone with the help of the sublingual-epiglottis ligament (lig.hyoepiglotticum), and to the thyroid cartilage - with the help of the shielded-ligated ligament (lig.thyroepiglotticum). The median transversely pubescent ligament (lig.cricothyroideum medianum) begins at the top of the arc of the cricoid cartilage and is attached to the lower edge of the thyroid cartilage. It keeps the thyroid cartilage from tipping it backwards. Perstetrachrheal ligament (lig.cricotracheale) connects the lower edge of the arc of the cricoid cartilage with the upper edge of the I cartilage of the trachea.

The walls of the larynx are formed by three membranes: mucosa, fibrous-cartilaginous and adventitia. The mucous membrane is lined with a multilayer ciliated epithelium. Only the vocal folds are covered with a flat multilayered epithelium. The intrinsic plate of the mucosa, represented by a loose fibrous connective tissue, contains a significant number of elastic fibers that do not have a specific orientation. Elastic fibers penetrate the perichondrium. In the thickness of its own plate of the mucous membrane there are numerous protein-mucous glands. Especially there are a lot of them in the folds of the vestibule and in the folds of the ventricles of the larynx. There are no glands in the region of the vocal cords. In the thickness of its own plate of the mucous membrane there is a significant amount of lymphoid tissue. Especially large clusters of it are found in the walls of the ventricles of the larynx. The muscular plate of the mucosa of the larynx is almost not developed. The submucosa of the larynx is compacted due to a significant amount of fibrous and elastic fibers, which form a fairly dense fibrous-elastic membrane. The fibro-elastic membrane (membrana fibroelastica) distinguishes two parts: a quadrangular membrane and an elastic cone.

The quadrangular membrane (membrana quadrangulitis) corresponds to the anterior larynx. Its upper edge reaches on each side scooped ongothoracic folds. The lower free edge is on each side in the thickness of the folds of the throat of the larynx. Elastic conus (conus elasticus) corresponds to the location of the podogolovoy cavity. The upper free edge of the elastic cone is thickened, stretched between the angle of the thyroid cartilage in front and the vocal outgrowths of the arytenoid cartilages from behind, forms the vocal cords (plicae vocales). The lower edge of the elastic cone is attached to the upper edge of the arc and to the anterior edges of the plate of the cricoid cartilage.

Fibrous cartilaginous larynx is represented by hyaline and elastic cartilage. Elastic cartilage forms an epiglottis, wedge-shaped and carob-shaped cartilage, a vocal appendage of arytenoid cartilages. Thyroid, cricoid and arytenoid cartilages of the larynx are hyaline. The adventitia is formed by a loose fibrous connective tissue.

The process of voice formation. The vocal folds (ligaments) of the larynx as they pass through the vocal chink of the exhaled air fluctuate and create a sound. The strength and height of the sound depends on the speed of air through the voice gap and on the tension of the vocal cords. Shades of speech are formed by contact with the lips, tongue, sky. The larynx cavity, the paranasal sinuses serve as sound resonators.

X-ray anatomy of the larynx. The larynx can be examined by X-ray in the anterior and lateral projections. On the roentgenogram, the hyoid bone is visible, the shadows of the larynx cartilage (thyroid, cricoid, epiglottis), the vocal cavity.

Innervation: the upper and lower laryngeal nerves (from the vagus nerve), the laryngeal-pharyngeal branches (from the sympathetic trunk).

Blood supply: the upper laryngeal artery (from the upper thyroid artery), the lower laryngeal artery (from the lower thyroid artery). Venous outflow: the upper and lower laryngeal veins (inflows of the internal jugular vein).

Outflow of lymph: into the deep lymph nodes of the neck (internal jugular, pregorticular nodes).

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Malformation of the larynx is rare. Some of them are completely incompatible with life, for example, with laryngotracheal pulmonary agenesis, atresia with complete obstruction of the larynx or trachea and bronchi. Read more..

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