The larynx (larynx) is a hollow organ of respiration and vocalization, which is involved in protecting the lower respiratory tract from foreign bodies.
It is projected onto the anterior cervical region.
It is located at the level between the 4th and the 6th cervical vertebrae.
- Superiorly, there is the hyoid bone
- Posteriorly, there is the laryngopharynx
- Laterally, there are common carotid arteries, internal jugular veins, and vagus nerves
- Anteriorly, it is covered with muscles lying below the hyoid bone and the superior parts of the thyroid gland
Visually, the larynx can be identified by the elevation on the anterior surface of the neck, the so-called laryngeal prominence (prominentia laryngea), commonly known as the Adam’s apple. This structure is more prominent in men.
The larynx of an adult has the following borders:
- The superior border passes at the level of the hyoid bone, and from the side of the spine at the level of the 6th cervical vertebra.
- The inferior border passes at the level of the 6th cervical vertebra in the area of transition to the trachea.
The laryngeal cavity (cavitas laryngis)
It has three sections:
The superior section, which is called the laryngeal vestibule (vestibulum laryngis). It is located between the laryngeal inlet and the false vocal folds, the so-called vestibular folds (plicae vestibulares)
The rima vestibuli (rima vestibula) is located between them
2. The middle section, which is called the interventricular section. It is located between the vestibular folds and the vocal folds (plicae vocales).
In this section, there is a recess on each side called the laryngeal ventricle (ventriculus laryngis)
The rima glottidis (rima vocalis) is located between the vocal folds.
3. The inferior section, which is called the infraglottic cavity (cavitas infraglottica). It is located between the vocal folds and the entrance to the trachea.
The cartilaginous skeleton, on which the laryngeal muscles are located, is the basis of the larynx.
Laryngeal cartilages (cartilagines laryngis) are interconnected by ligaments. The larynx includes three single and three paired laryngeal cartilages.
1. The cricoid cartilage (cartilago cricoidea), which is a ring-shaped cartilage of the laryngeal skeleton.
The anterior narrow part is called the arch (arcus)
The inferior wide part is called the lamina (lamina)
On the lateral surfaces of the cricoid cartilage, there are superior and inferior articular surfaces for articulation with the arytenoid and thyroid cartilages, respectively.
2. The thyroid cartilage (cartilago thyreoidea), which is the largest cartilage of the larynx. It has the shape of a shield. This cartilage is located above the cricoid cartilage.
Two quadrangular laminae of cartilage are fused in the anterior part and form a ridge, at the superior edge of which there is the superior notch (incisura thyroidea superior)
At the inferior edge, there is the inferior notch (incisura thyroidea inferior)
The right lamina (lamina dextra)
and the left lamina (lamina sinistra)
have the horns in their posterior part:
The superior horn (cornu superius)
the inferior horn (cornu inferius)
These horns are the place where the hyoid bone connects with the cricoid cartilage.
The oblique line (linea obliqua), which is the place where some of the muscles of the larynx insert, passes to the inferior border on the external surface from the superior horns.
3. The epiglottic cartilage (cartilago epiglottica) or epiglottis (epiglottis), which is a thin lamina, the narrowed part of which connects with the thyroid cartilage just below its superior notch.
The narrowed part of the epiglottis is called the stalk (petiolus)
The enlarged part is free and facing up. Also, on the surface of the cartilage, there is the epiglottic tubercle (tuberculum epiglotticum).
Paired laryngeal cartilages:
1. The arytenoid cartilage (cartilago arytenoidea), which has a triangular shape.
It connects with the superior part of the cricoid cartilage. The inferior part of the cartilage is expanded and has two processes: the vocal process (processus vocalis), which is directed anteriorly and connects to the vocal cords.
And the muscular process (processus muscularis), which is directed laterally to the vocal process.
On the lateral side, a triangular fovea (fovea triangularis) is located between the vocal and muscular processes
This is the site of attachment of the vocalis muscle (m. vocalis).
2. The corniculate cartilage (cartilago corniculata)
It is a small cartilage located at the apex of the arytenoid cartilage. These cartilages are not always present in the normal anatomy of the larynx.
3. The cuneiform cartilage (cartilago cuneiformis)
It is located in the thickness of the ary-epiglottic fold, where it forms a cuneiform tubercle (tuberculum cuneiforme) on each side, which is often rudimentary.
4. The triticeal cartilage (cartilago triticea), which lies in the thickness of the lateral thyrohyoid ligament.
The laryngeal cartilages form the following joints:
1. The cricothyroid joint (articulatio cricothyroidea), which is formed by the lateral surface of the cricoid cartilage and the inferior horn of the thyroid cartilage. The thyroid cartilage is mobile and increases or decreases the tension of the vocal folds during vocalization, changing the pitch of the voice.
2. The crico-arytenoid joint (articulatio cricoarytenoidea), which is formed by the inferior surface of the arytenoid cartilage and the superior articular surface of the lamina of the cricoid cartilage. This joint is involved in the expansion of the rima glottis.
In addition, the larynx has many ligaments:
1. The median thyrohyoid ligament (lig. thyrohyoideum medianum)
2. The lateral thyrohyoid ligament (lig. thyrohyoideum laterale)
These ligaments are parts of the thyrohyoid membrane (membrana thyrohyoidea).
This membrane connects the larynx to the hyoid bone. A neurovascular bundle of the larynx passes through an opening in the external part of the thyrohyoid membrane. In fact, this membrane suspends the larynx to the hyoid bone.
3. The cricothyroid (conoid) ligament (lig. cricothyroideum), which passes from the superior border of the arch of the cricoid cartilage to the inferior border of the thyroid cartilage. The cricothyroid ligament is a very important anatomical structure. During asphyxia, it is incised and a cricothyrotomy is performed, which restores breathing.
4. The cricotracheal ligament (lig. cricotracheale), which passes between the cricoid cartilage and the first ring of the larynx, connecting them together.
5. The thyro-epiglottic ligament (lig. thyroepiglotticum), which connects the epiglottis with the thyroid cartilage.
6. The hyo-epiglottic ligament (lig. hyoepiglotticum), which connects the epiglottis with the body of the hyoid bone.
7. The vocal fold (plica vocalis), which covers the vocalis muscle.
8. The ary-epiglottic ligament (lig. aryepiglottica), which passes between the lateral border of the epiglottis and the internal border of the arytenoid cartilage.
9. The median glosso-epiglottic fold (plica glossoepiglottica mediana)
10. The lateral glosso-epiglottic fold (plica glossoepiglottica lateralis)
These folds connect the median and the lateral part of the root of the tongue with the anterior surface of the epiglottis.
The laryngeal muscles are divided into several groups.
The external laryngeal muscles, which directly provide movement of parts of the organ.
1. These are the muscles that attach to the thyroid cartilage and bones of the skeleton:
- The sternothyroid muscle (m. sternothyroideus)
- The thyrohyoid muscle (m. thyrohyodeus)
2. And the muscles, which are attached to the hyoid bone and bones of the skeleton:
- The sternohyoid muscle (m. sternohyoideus)
The omohyoid muscle (m. omohyoideus)
- The stylohyoid muscle (m. stylohyoideus)
- The digastric muscle (m. digastricus)
- The geniohyoid muscle (m. geniohyoideus)
The internal laryngeal muscles participate directly in breathing and vocalization.
They are divided into three subgroups.
Muscles that strain the vocal ligaments:
1. The cricothyroid muscle (m. cricothyroideus), which is located between the arch of the cricoid cartilage and the inferior border of the thyroid cartilage. This muscle narrows the rima glottidis.
2. The vocalis muscle (m. vocalis), which is the largest muscle of the vocal fold. It passes from the internal surfaces of the thyroid cartilage to the vocal process of the arytenoid cartilage. A thin elastic strip of tissue, which is directly involved in vocalization, runs along the medial border of the muscle.
Muscles that expand the rima glottidis:
1. The posterior crico-arytenoid muscle (m. cricoarytenoideus posterior), which goes from the cricoid cartilage to the muscular process of the arytenoid cartilage. This is the only muscle that expands the rima glottis. With its paralysis, breathing stops.
Muscles that constrict the rima glottidis:
1. The lateral crico-arytenoid muscle (m. cricoarytenoideus lateralis), which is a paired muscle that runs along the lateral surface of the cricoid cartilage and attaches to the muscular process of the arytenoid cartilage.
The oblique arytenoid muscle (m. arytenoideus obliquus), which is a paired muscle that passes from the muscular process of one arytenoid cartilage to the opposite arytenoid cartilage
3. The transverse arytenoid muscle (m. arytenoideus transversus), which connects the posterior surfaces of the arytenoid cartilages.
4. The thyro-arytenoid muscle (m. thyroarytenoideus), which passes from the internal surface of the thyroid cartilage to the lateral border of the arytenoid cartilage. During contraction, the arytenoid cartilage is displaced.
Also, the internal laryngeal muscles include the following two:
1. The ary-epiglottic muscle (m. aryepiglotticus), which passes between the apex of the arytenoid cartilage and the lateral borders of the epiglottis. This muscle is involved in the formation of the aryepiglottic ligament. It participates in swallowing, covering the laryngeal inlet so that food enters the esophagus.
2. The thyro-epiglottic muscle (m. thyroepiglotticus), which is located between the internal surface of the angle of the thyroid cartilage and the lateral border of the epiglottis. It raises the epiglottis and opens the laryngeal inlet.
The larynx is supplied with blood by two major arteries:
- The superior laryngeal artery (а. laryngea superior), which arises from the superior thyroid artery (а. thyroidea superior), which in turn arises from the external carotid artery (a. carotis externa). The superior laryngeal artery passes through an opening in the outer part of the thyrohyoid membrane and forms a neurovascular bundle with the eponymous vein and nerve.
Inside the larynx, the superior laryngeal artery splits into branches. The largest of them is the middle laryngeal artery (a. laryngea media), which anastomoses with the eponymous artery on the opposite side in the area of the conoid ligament.
- The inferior laryngeal artery (a. laryngea inferior), which is a branch of the inferior thyroid artery (a. thyroidea inferior) that arises from the thyrocervical trunk (truncus thyrocervicalis).
Venous blood drains from the larynx in two ways:
- Through the superior thyroid vein (v. laryngea superior) into the internal jugular vein (v. jugularis interna)
- Through the inferior thyroid vein (v. laryngea inferior) into the brachiocephalic vein (v. brachiocephalica)
There are the superior and inferior parts of the lymph drainage:
- The superior part, which is located in the area of vestibular folds and laryngeal ventricles. From here, the lymph goes through the vessels along the neurovascular bundle of the larynx to the deep cervical lymph nodes located along the deep jugular vein.
- The inferior part, which includes lymphatic vessels under and above the cricoid cartilage, which insert into the pre-epiglottic lymph nodes. Also, part of the lymph flows into the deep cervical lymph nodes lying along the deep jugular vein.
Innervation of the laryngeal muscles is carried out by two branches of the vagus nerve:
- The superior laryngeal nerve (n. laryngeus superior), which arises from the vagus nerve in the region of the nodose ganglion of the vagus nerve (ganglion nodosum n. vagi). Behind the greater horn of the hyoid bone, the superior laryngeal nerve splits into two branches: the external branch (r. externus), which innervates the cricoid muscle, the internal branch (r. internus), approaches the mucous membrane of the larynx in the form of sensitive branches.
- The inferior laryngeal nerves (n. laryngeus inferior s.n. recurrens), which are extensions of the right and left recurrent nerves that branch off from the vagus nerve. It innervates all internal laryngeal muscles, except the cricothyroid muscle, and provides sensitive innervation of the laryngeal mucosa in its inferior part and vocal folds. The right recurrent nerve arises from the vagus nerve at the level of the subclavian artery, and the left one arises at the site of the circumference of the aortic arch by the vagus nerve. The recurrent nerves on the right and left pass up to the larynx. Along the way, they give off numerous branches that innervate the trachea and esophagus.
- The sympathetic nerves of the larynx, which arise from the superior cervical sympathetic cervicothoracic (stellate) ganglion (ganglion stellatum).
Anatomy of the larynx
- Cartilages of the larynx
- cartilagines laringis
- Cricoid cartilage
- cartilago cricoidea
- Thyroid cartilage
- cartilago thyreoidea
- Superior notch
- incisura thyroidea superior
- Inferior thyroid notch
- incisura thyroidea inferior
- Right and left laminae
- lamina dextra et sinistra
- Superior and inferior horns
- cornua superiora et inferiora
- Oblique line
- linea oblique
- Epiglottic cartilage
- cartilago epiglotica
- Arytenoid cartilage
- cartilagines arytaenoidea
- Vocal process
- processus vocalis
- Muscular process
- processus muscularis
- Triangular fovea
- fovea triangularis
- m. vocalis
- Corniculate cartilage
- cartilagines corniculatae
- Cuneiform cartilage
- cartilagines cuneiforms
- Cuneiform tubercle
- tuberculum cuneiforme
- Cricothyroid joint
- articulatio cricothyreoidea
- Cricoarytenoid joint
- articulatio cricoarytenoidea
- Median and lateral thyrohyoid ligaments
- lig. thyroideum medium et lateralis
- Thyrohyoid membrane
- membrana thyrohyoidea
- Thyroepiglottic ligament
- Hyoepiglottic ligament
- lig. hyoepigtotticum
- Cricotracheal ligament
- lig. cricotracheate
- Cricothyroid ligament
- lig. cricothyroideum
- Elastic membrane of the larynx
- membrana elastica laryngis
- Vocal fold
- plica vocate
- Aryepiglottic ligament
- lig. aryepiglottica
- Median and lateral glosso-epiglottic folds
- lig. gtossoepigtotticum medium et tateratis
- Epiglottic valleculae
- valleculae epiglotticae
- Sternothyroid muscle
- m. sternothyroideus
- Thyrohyoid muscle
- m. thyrohyoideus
- Sternohyoid muscle
- m. sternohyoideus
- Omohyoid muscle
- m. omohyoideus
- Stylohyoid muscle
- m. stylohyoideus
- Digastric muscle
- m. digastricus
- Geniohyoid muscle
- m. geniohyoideus