Generality
The epiglottis is an elastic cartilaginous structure, located behind the tongue, which overhangs the upper opening of the larynx .
Its main function is to prevent liquids, food and saliva from ending up in the respiratory tract (ie "going sideways"). For this reason, during swallowing, the epiglottis reverses backwards, temporarily covering the opening of the larynx and directing the alimentary bolus towards the esophagus and the stomach .
The epiglottis can be affected by various pathological conditions, including infections, edema, pericondrites, cysts, congenital malformations, tumors and inflammatory processes.
If the epiglottis does not function properly, there is a risk that part of the food ends up in the lower airways, predisposing to the development of pneumonia ab ingestis .
Epiglottis: What it is
The epiglottis is a thin lamina covered by a mucous membrane, made up of elastic cartilage and, in part, of fibrous tissue. This structure has a triangular shape, similar to a leaf, rounded at the top (free margin) and narrower at the base (fixed portion). At the lower end, the epiglottis is equipped with a peduncle that allows it to be connected, by means of the thyroid-tear ligament, to the thyroid cartilage.
The epiglottis separates the tongue from the laryngeal cavity and projects obliquely upwards, almost forming a sort of " valve ". Its main function consists, in fact, in preventing the access of chewed foods inside the airways, in the act of swallowing.
Where is it
The epiglottis is part of the laryngeal complex . This fibrocartilaginous structure is located at the root (or base) of the tongue, at the top of the larynx .
In particular, the epiglottis is found:
- Behind the tongue and posteriorly with respect to the body of the hyoid bone (unequal and median bone which is found at the root of the tongue, at the level of the fourth cervical vertebra);
- In front of the upper opening of the larynx (or laryngeal entrance ).
At the resting state (ie when the subject does not speak or swallow), the epiglottis is obliquely directed from the bottom to the top and from the front to the back.
Conformation and relations with other structures
The epiglottis presents:
- A free margin : wide and rounded (sometimes, indented on the median line), it heads upwards;
- A fixed portion : also called peduncle, is the part of the long, narrow epiglottis covered by the laryngeal mucosa. The fixed portion of the epiglottis is turned towards the laryngeal cavity and is connected by an elastic ligament (called the thyroid pedicle ligament ) to the laryngeal prominence of the thyroid cartilage .
The outline of the free portion of the epiglottis is characterized by:
- Upper extreme : it has a rounded shape, convex in the whole, with a slight depression in the center, it continues with the lateral margins;
- Two side margins : they appear jagged and provide an attachment, at the bottom, to the ariepiglottic folds . The latter are structures of the mucous membrane that extend up to the apex of the arytenoid cartilages, ie the cartilages of the laryngeal skeletal complex that provide a base of attack for the vocal ligament and intrinsic laryngeal muscles . The folds contain the aryepiglottic muscle.
The anterior surface of the epiglottis (also called the lingual face ) is coated:
- In the upper half, from a mucosa similar to that of the oral cavity (in detail, it is a non-keratinized stratified paved epithelium);
- In the lower half, from the fatty tissue that fills the thyroid epiglottic space.
The posterior surface of the epiglottis (or laryngeal face ), facing towards the cavity of the larynx, is covered by a respiratory mucosa .
The cartilaginous surfaces are scattered posteriorly by many small holes and dimples, where the small glands of the mucous membrane that cover them are nested.
At the level of the epiglottitis the branches of the laryngeal nerve run .
What is it for?
The epiglottis has the function of preventing liquids and the alimentary bolus, chewed in the mouth, from entering the trachea during swallowing . To accomplish this task, the cartilaginous structure lowers over the opening of the larynx, as if to close it temporarily.
In fact, while swallowing, the base of the tongue (ie the most backward part of the oral cavity) makes movements that bring it to rest on the epiglottis. As a result of the passive pressure caused by the tongue and aryepiglottic muscles, the epiglottis is thus induced to tip backwards, closing access to the airways .
Normally, the epiglottis removes food and liquids from the opening of the larynx by directing them into the alimentary canal.
The epiglottis is not essential for breathing or does not perform important functions with regard to speech .
Curiosity: epiglottis and linguistic sounds
In certain languages, the epiglottis performs a phonetic task: by contracting and changing position, it participates in the expression of epiglottal consonants ; this type of vocal sound is quite rare. Epiglottal consonants are found, for example, in some dialects and variants of Arabic, in the Haida language of Native Americans (prevalent mainly in Canada) and in the Agul language (spoken in the North-East Caucasian area).
Epiglottis disorders: Causes
The epiglottis is subject to various disorders, partly related to the pathological conditions that affect the hypopharynx (lower portion of the throat), the base of the tongue and the larynx.
These morbid processes may include:
- Infections (epiglottitis, oral HPV etc.);
- Swelling (edema) from allergies, traumas or inflammatory processes;
- Perichondritis (inflammation of the cartilaginous components);
- Cysts and polyps;
- Benign and malignant tumors (eg squamous cell carcinoma, papillomas and fibroids);
- Malformation or congenital absence (rare occurrence).
A malfunction of the epiglottis can cause food to enter the lower airways, reaching the lungs. This situation predisposes to the development of a pneumonia ab ingestis (or inhalation pneumonia).
Inflammation of the epiglottis can be caused by:
- Traumatic events (the epiglottis is vulnerable above all to abrasion, due to its relationship with the digestive tract);
- Exposure to chemical agents;
- Ingestion of excessively hot foods or boiling liquids;
- Infectious processes.
Allergic reactions and anaphylactic shock can sharply induce a swelling of the epiglottis and subglottal region, located just below the vocal cords before the trachea. This phenomenon manifests itself with a serious respiratory difficulty (dyspnea) which can lead, if not treated urgently, to death by suffocation or cardio-circulatory complications .
epiglottitis
One of the pathological processes worth investigating is epiglottitis . This condition can have a very serious course, especially when it occurs during childhood.
The epiglottitis is an infection of the epiglottis, which can lead to sudden obstruction of the respiratory tract due to the swelling of the supraglottic and neighboring tissues.
The infection of the epiglottis is of bacterial nature: usually, the pathogens spread locally starting from the nasopharynx, previously colonized. The result is a supraglottic cellulite that involves a marked inflammation of the epiglottis .
The main causative microorganisms include: Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus parainfluenzae, β-haemolytic streptococci, Klebsiella pneumoniae and Branhamella catarrhalis .
Symptoms of epiglottis infection include:
- Sore throat intense (pharyngitis);
- Dysphagia;
- High fever (39-40 ° C);
- drooling;
- Inspiratory stridor;
- Breathing difficulty (dyspnea);
- Compromise of the general state.
The epiglottitis begins suddenly and can rapidly progress towards respiratory failure, as the inflamed tissues mechanically obstruct the airway. This can lead to asphyxia and evolve until the patient dies.
The diagnosis requires the direct observation of the supraglottic structures, which must be performed only in the presence of resuscitation specialists: in fact, under epiglottitis conditions, the procedure can determine the reflex spasm of the glottis, which leads to acute respiratory failure.
Epiglottitis therapy includes respiratory support ( nasotracheal intubation or, less often, tracheotomy) and administration of antibiotic drugs (such as ceftriaxone or ampicillin).
Epiglottitis from Haemophilus influenzae type B (HiB)
In the past, one of the major etiological agents of epiglottid infection in children was Haemophilus influenzae type B, which we also remember to be one of the main pathogens responsible for meningitis . Today, thanks to the spread of anti-HiB vaccination, epiglottitis is rare in pediatric age, but cases still occur in unvaccinated adults and children.
Infection with Haemophilus influenzae type B can spread, starting from the epiglottis, via the bloodstream.
Symptoms and Complications
The symptomatology of the disorders affecting the epiglottis varies according to the etiology .
Given the location, the following manifestations are common:
- Difficulty swallowing ( dysphagia );
- Painful swallowing ( odynophagia );
- Pharyngodinia ;
- Sialorrhea .
Furthermore, the following symptoms are possible:
- Dyspnoea;
- tachypnea;
- Dysphonia.
If inflamed or edematous, the epiglottitis represents a serious problem, which when it is not caught in time and treated appropriately, can lead to very serious complications.
Diagnosis
The diagnosis of epiglottis pathologies is fundamentally based on the direct observation of the structures involved.
The most useful investigation for this purpose is laryngoscopy, a painless procedure that allows the doctor to directly inspect the epiglottis and the larynx. This examination is performed with a fiber optic laryngoscope, which has its own lighting and is introduced into the throat through the nasal cavity ( flexible laryngoscope ) or is placed on the tongue ( rigid fiberscope ). Both instruments allow to evaluate the motility of the epiglottis and the possible presence of diffuse edema or localized swelling, hyperemia or cysts or anomalous masses.
To know
Examination of the pharynx or larynx in children with epiglottitis can accelerate complete airway obstruction . For this reason, if the diagnosis is suspected, flexible fiber optic laryngoscopy should be performed in the operating room, in the presence of a team specialized in emergency resuscitation.
Even an X-ray ( RX ) or other imaging studies can be useful to highlight some pathological processes affecting the epiglottis.
If an epiglottis infection is suspected by the doctor, the microbiological culture of samples collected at supraglottic tissues is also indicated, in search of the causative microorganism.
Treatment
Treatment of disorders affecting the epiglottis depends on the triggering causes.
In general, the airway must always be guaranteed . Some pathological processes characterized by epiglottis edema can predispose, in fact, to an obstruction of the airways. This can quickly lead to respiratory failure.
In patients with epiglottitis, for example, the airways should be protected, preferably with nasotracheal intubation, until the clinical picture is stabilized. Alternatively, a tracheotomy is performed.
If a respiratory arrest occurs before an airway has been re-established, the self- expanding mask and balloon ventilation (AMBU) may represent a temporary life-saving measure .
Infections
If an epiglottis infection is suspected, an β-lactamase-resistant antibiotic such as ceftriaxone should be administered to the patient empirically, pending the results of culture tests and sensitivity tests.
The epiglottitis caused by Haemophilus influenzae B can be effectively prevented with the anti-HiB vaccine. In Italy, immunization is included in the hexavalent vaccination (as it contains 6 vaccines that confer protection against: Diphtheria-Tetanus-Pertussis, Poliomyelitis, Hepatitis B and, precisely, HiB) provided for all children. The vaccination cycle consists of three doses, to be practiced within the first year of life, at the 3rd, 5th and 11th month. The monovalent HiB vaccine is also available.
