Generality
The larynx is the organ of the throat, tubular in shape, which houses the vocal cords and regulates the passage of air into and out of the trachea.
Representing the last stretch of the so-called upper airways, the larynx is a complex of several cartilages, which are held together by a series of ligaments, membranes and muscles.
Including between the III cervical vertebra and the VI cervical vertebra, the larynx can be divided into 3 sections, whose names, starting from the upper section, are: supraglottis, glottis and subglottis.
The larynx is involved in phonation, breathing and the mechanism that prevents food from entering the path of the trachea and obstructing the respiratory tract.
The larynx may be at the center of various medical conditions, including, for example, laryngitis, throat cancer and laryngospasm.
What is the Larynx?
The larynx is the unequal internal organ, shaped like a tube, predominantly of a cartilaginous nature, with a seat in the antero-superior compartment of the neck, which puts the pharynx in communication with the trachea .
The larynx is one of the anatomical components of the throat, it belongs to the respiratory system and is the seat of the vocal cords .
In anatomy, the term "throat" includes the pharynx, the larynx and the proximal (or initial) parts of the esophagus and trachea .
The larynx in the respiratory tract
Inside the respiratory system, the larynx is the last part of the so-called upper airway ; after it, in fact, the so-called lower airways begin with the trachea.
- The upper airways begin with the nasal cavities and the oral cavity ; then they continue with the subdivisions of the pharynx known as nasopharynx and oropharynx ; finally, they end with the larynx.
- Immediately following the upper airway, the lower airways begin with the trachea; subsequently, they continue with the bronchial tree (ie bronchi and bronchioles ); finally, they end with the lungs and the system of the alveoli .
Synonyms
Because it houses the vocal cords, the larynx is also known as a vocal box .
Anatomy
Approximately 5 centimeters long, the larynx is a tubular formation of different cartilaginous components, which are held together by a series of muscles, ligaments and fibro - connective membranes .
Observed inside the human body, the larynx extends vertically from the III cervical vertebra (vertebra C3) to the VI cervical vertebra (vertebra C6).
Internally, the larynx is lined with respiratory epithelium (ciliated columnar pseudostratified epithelium), except in the vocal cords, which present a stratified squamous epithelium .
According to the most traditional anatomical descriptions, the larynx can be divided into 3 overlapping sections, whose names are, starting from the top: supraglottis, glottis and subglottis .
Location of the Larynx
The larynx takes place in the throat, below the pharynx, in front of the esophagus and exactly above the trachea, with which it communicates.
The larynx is an internal organ of the anterior-superior compartment of the neck.
Externally, the larynx can be placed at the same height as the Adam 's apple, that is, the anterior protrusion of the neck which is notoriously more evident in men than in women.
Subdivisions of the Larynx
SOPRAGLOTTIDE
The supraglottic represents the upper section of the larynx; located on the border with the oropharynx (second subdivision of the pharynx), it goes from the laryngeal cartilage known as epiglottis to the so-called vestibular folds (or false vocal cords ).
GLOTTIS
The glottis is the intermediate section of the larynx; immediately following the sopraglottis, it is the site of the vocal cords as well as the regulated passage way (see the section dedicated to the vocal cords), which allows the inhaled air to enter or escape from the trachea.
subglottis
The subglottis is the lower section of the larynx; its course begins immediately after the glottis and ends at the lower edge of the laryngeal cartilage known as cricoid cartilage .
At the point where it ends, the subglottis is in connection with the trachea.
Larynx cartilages
The larynx consists of 2 groups of cartilages: the group of unequal cartilages (or single cartilages), which include the epiglottis, the thyroid cartilage and the cricoid cartilage, and the group of even cartilages (or coupled cartilages), which includes the two aritenoid cartilages, the two corniculate cartilages and the two cuneiform cartilages .
The larynx is therefore formed by 6 different cartilages: the 3 single cartilages, called epiglottis, thyroid cartilage and cricoid cartilage, and the 3 coupled cartilages, known as arytenoid cartilages, corniculate cartilages and cuneiform cartilages.
ARTILAGES LEARN OF LARYNGE
- Epiglottis: the epiglottis is an elastic cartilage, morphologically similar to a spoon, which takes place on the upper part of the larynx, in the so-called supraglottis.
The epiglottis is comparable to a lid that serves to close the entrance to the larynx, at the moment when the human being is eating, so as to prevent the food from ending up in the trachea and obstructing breathing.
In normal conditions (ie when the human being is not eating), the epiglottis assumes a position such that the air has complete freedom to enter and exit the larynx.
- Thyroid cartilage: placed on the anterior portion of the larynx, the thyroid cartilage is the cartilaginous structure that forms, on the outside of the neck, the aforementioned Adam's apple.
On the thyroid cartilage, one of the two ends of the ligament joins the larynx to the hyoid bone ; this ligament is called lateral thyroid ligament.
- Cricoid cartilage: the cricoid cartilage is a ring of hyaline cartilage, which forms the lower portion of the larynx.
A link between the larynx and the trachea, the cricoid cartilage is connected to the thyroid cartilage, by means of the so-called cricothyroid ligament.
PAPER PAPERS EQUAL TO LARINGE
- Arytenoid cartilages: located between the glottis and the supraglottis, and similar to 3-sided pyramids, the two arytenoid cartilages are the most important even cartilages of the larynx; in fact, the insertion of the vocal cords and the movement of the latter depends on them.
- Corniculate cartilages: similar, as the name implies, to the horns, the two corniculate cartilages reside on the apex of the arytenoid cartilages.
Corniculate cartilages are particularly elastic.
- Cuneiform cartilages: morphologically similar to a clave, the two cuneiform cartilages reside in front of the corniculate cartilages.
Like the corniculate cartilages, the cuneiform cartilages have a particular elasticity.
Vocal cords
Located at the level of the glottis and the most representative elements of this section of the larynx, the vocal cords are the particular anatomical formations that, through their vibration, allow phonation (ie the emission of sounds and words from the mouth).
Dominated by two folds known as vestibular folds (or false vocal cords), the vocal cords are a pair of flaps, whose constitution, if analyzed from the most superficial area to the most intimate part, take part:
- A stratified squamous epithelium . This epithelium serves to protect the vocal cords from possible foreign bodies, coming from the outside, which could damage you or enter the larynx.
- A gelatinous layer, rich in glycosaminoglycans, called Reinke space . The space of Reinke is fundamental to the vibration of the vocal cords and consequently to the process of emission of sounds and words from the mouth;
- The vocal ligaments . Composed of a particularly elastic fabric, they are used to support the vocal cords.
Their posterior end is anchored to the arytenoid cartilage, while their anterior end is attached to the thyroid cartilage.
- The vocal muscles (or thyroid thyroid muscles). Located laterally to the vocal ligaments, they are the thin muscles of the larynx that relax the vocal cords.
The vocal cords delimit a variable space, called the glottis rhyme and only the glottis (like the homonymous section of the larynx), which represents the access route into and out of the inspired wind trachea.
The vocal cords are poorly vascularized (avascular) and have a whitish coloring; on their surface, they have a mucous layer.
Ligaments and Laryngeal Membranes
The larynx includes 2 groups of ligaments and fibro-connective membranes: the group of ligaments and extrinsic membranes and the group of ligaments and intrinsic membranes .
In the group of ligaments and extrinsic membranes, all those ligaments and membranes are included, with one end attached to the larynx and one end attached to an anatomical structure different from the larynx; in the group of ligaments and intrinsic membranes, instead, all those ligaments and all those membranes with both ends connected to the larynx and deputies to keep the various laryngeal cartilages together are included.
EXTRINSIC TIGHTS AND MEMBRANES OF LARYNGE
The extrinsic ligaments of the larynx are:
- The thyroid membrane . Starts from the upper edge of the thyroid cartilage to the hyoid bone; presents the perforations for the arteries and upper laryngeal veins, and for the internal laryngeal nerve.
- The median thyroid ligament . It is an antero-medial thickening of the thyroid membrane; participates with the latter in the connection between the thyroid cartilage and the hyoid bone.
- Lateral thyroid ligament . It is a postero-medial thickening of the thyroid membrane; it contributes with the latter to the connection between the thyroid cartilage and the hyoid bone.
- The ioepiglottic ligament . It is the ligament that joins the hyoid bone to the anterior aspect of the epiglottis.
- The cricotracheal ligament . It is the ligament that connects the cricoid cartilage to the trachea.
- The median cricothyroid ligament . It is a separate thickening of the cricothyroid ligament (an intrinsic ligament of the larynx), whose task is to join the thyroid to the cricoid cartilage.
INTRINSIC LAMBS OF LARYNGE
The intrinsic ligaments of the larynx are:
- The cricothyroid ligament . It is an important ligament, which finds insertion on 3 distinct cartilages of the larynx: the cricoid cartilage, the thyroid cartilage and the arytenoid cartilage;
the cricothyroid ligament and the vocal ligament depart from the cricothyroid ligament.
- The quadrangular membrane . Starts from the anterolateral portion of the arytenoid cartilage to the lateral margin of the epiglottis; it has a free upper margin and a thickened lower margin, which gives rise to the so-called vestibular ligament (see next point).
- The vestibular ligament . It is the intrinsic ligament of the larynx that forms the false vocal cords.
- The vocal ligament . Already mentioned on more than one occasion, it is the ligament which, situated where there are vocal cords, joins the arytenoid cartilage to the thyroid cartilage.
Larynx muscles
The larynx comprises 2 large muscle groups: the intrinsic muscle group and the extrinsic muscle group.
The group of intrinsic muscles of the larynx gathers all those muscles with both ends anchored to the larynx; the group of extrinsic muscles of the larynx, instead, includes all those muscles with one end tied to the larynx and one end hooked to an anatomical structure different from the larynx.
INTRINSIC MUSCLES OF LARYNGE
The intrinsic muscles of the larynx are used for phonation and breathing.
Specifically, these muscles are:
- The cricothyroid muscle . It is the muscle delegated to stretch and stretch the vocal cords;
- The posterior cricoaritenoid muscle . It is the muscle that externally abducts and rotates the arytenoid cartilages, so as to abduct the vocal cords and open the rhyme of the glottis.
- Lateral cricoaritenoid muscle . It is the muscle that internally adduces and rotates the arytenoid cartilages, in such a way as to add the vocal cords and to close the rhyme of the glottis.
- The transverse arytenoid muscle . It is the muscle that adduces the arytenoid cartilages, so as to favor the closure of the glottis.
- The oblique arytenoid muscles . It is the muscle that reduces the distance between the arytenoid cartilages, which induces the closure of the glottis.
- The thyroid thyroid muscles . It is the muscle responsible for the relaxation of the vocal cords; the relaxation of the vocal cords produces a lowering of the tone of the voice.
EXTRINSIC MUSCLES OF LARYNGE
The extrinsic muscles of the larynx are muscles that, with one or more specific functions, associate an action of support and maintenance in position of the larynx itself.
More in detail, these muscles are: the sternum thyroid muscle, the homoioid muscle, the sternum hyoid muscle, the lower constrictor muscle, the thyroid muscle, the digastric muscle, the hygienic stylus muscle, the mylohyoid muscle, the genioioid muscle, the muscle ioglossus and the genioglossus muscle.
Innervation of the Larynx
Two branches of the vagus nerve ( X cranial nerve ), known as the recurrent laryngeal nerve and the upper laryngeal nerve, are concerned with the sensory and motor innervation (ie the muscles) of the larynx.
- The recurrent laryngeal nerve provides the sensory innervation of the subglottis; in addition, it controls all the intrinsic muscles of the larynx, except for the cricothyroid muscle.
- The upper laryngeal nerve provides sensory innervation of the glottis and supraglottis; in addition, it controls the intrinsic laryngeal muscle excluded from the recurrent laryngeal nerve, namely the cricothyroid muscle.
Please note
With laryngeal motor innervation we refer only to the innervation of the intrinsic laryngeal muscles.
Blood Circulation in the Larynx
The inflow of oxygenated blood to the larynx belongs to the upper laryngeal artery and to the inferior laryngeal artery :
- The upper laryngeal artery is a branch of the superior thyroid artery, which in turn is a branch of the external carotid artery.
When reaching the larynx, this artery follows the inner branch of the superior laryngeal nerve;
- The inferior laryngeal artery, on the other hand, is a branch of the inferior thyroid artery, which derives from the thyrocervical trunk.
The laryngeal vein and the inferior laryngeal vein provide the drainage from the larynx of the oxygen-poor blood:
- The upper laryngeal vein drains the oxygen-poor blood in the superior thyroid vein, which flows into the internal jugular vein;
- The inferior laryngeal vein, instead, drains the oxygen-poor blood in the inferior thyroid vein, which flows into the left brachiocephalic vein.
Borders and Reports of the Larynx
In summary, the larynx borders on:
- The pharynx, superiorly;
- The esophagus, posteriorly;
- The trachea, inferiorly;
- The skin that covers the anterior-superior compartment of the neck, anteriorly.
Function
The larynx covers 3 functions, all equally important:
- Contributes to the respiratory process, channeling air to the lower airways (trachea, bronchi, bronchioles and lungs);
- It allows the phonation, through the vibration of the vocal cords, operated by the contraction of the intrinsic muscles;
- Thanks to the cartilage called epiglottis, it prevents the food being swallowed from entering the trachea and obstructing the airways.
diseases
The larynx may be at the center of various medical conditions, among which the most relevant are: laryngitis, throat cancer, vocal cord paralysis, laryngospasm and pharyngo-laryngeal reflux .
Laryngitis
Laryngitis is inflammation of the larynx or vocal cords.
Responsible for symptoms such as hoarseness, sore throat, loss of voice etc., laryngitis can arise due to an infection of the upper airways (usually a viral infection) or due to factors such as cigarette smoking (smoking), alcohol abuse, inhalation of throat irritants etc.
Throat cancer
With the expression "throat tumor", doctors indicate a generally malignant neoplasm, which originated from the uncontrolled proliferation of one of the cells belonging to the pharynx, larynx or palatine tonsils.
At present, the precise causes of throat cancer are unknown; it is, however, a fact that factors such as cigarette smoking and alcohol abuse increase the risk of the formation of the neoplasm in question.
Throat cancer is responsible for not very specific symptoms, such as pain in the throat, cough, hoarseness, difficulty swallowing etc., which however have the peculiarity of being persistent (and this feature must represent an alarm bell).
Paralysis of the Vocal Chords
Paralysis of the vocal cords is the condition that arises following damage to the recurrent laryngeal nerve, ie the nerve that controls the laryngeal muscles responsible for the movement of the vocal cords.
The paralysis of the vocal cords prevents the vibration of the vocal cords themselves as well as the correct opening of the glottis; this means that it can represent an obstacle not only to phonation, but also to breathing.
laryngospasm
According to the most classic of definitions, it is the involuntary and uncontrolled contraction of the laryngeal muscles, with consequent abnormal narrowing of the glottis and vocal cords.
The phenomenon of laryngospasm determines the temporary block of respiration ; the inhaled air, in fact, cannot pass into the trachea, because the rhyme of the glottis is closed.
Pharyngo-laryngeal reflux
Responsible for burning in the stomach, hoarseness, a lump in the throat and sore throat, pharyngolaryngeal reflux is the pathological phenomenon in which the acidic contents of the stomach rise up all over the esophagus and reaches the anatomical districts corresponding to pharynx and larynx .
