Epiglottis
Encyclopedia
The epiglottis is a flap that is made of elastic cartilage
tissue covered with a mucous membrane
, attached to the entrance of the larynx
. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. The term, like tonsil
s, is often incorrectly used to refer to the uvula
. There are taste bud
s on the epiglottis.
, the opening between the vocal folds
.
It is normally pointed upward while one is breathing
with its underside functioning as part of the pharynx
, but while one is swallowing
, elevation of the hyoid bone
draws the larynx
upward; as a result, the epiglottis folds down to a more horizontal position, with its superior side functioning as part of the pharynx. In this manner it prevents food from going into the trachea
and instead directs it to the esophagus
, which is posterior.
The epiglottis is one of nine cartilaginous structures that make up the larynx (voice box). While one is breathing, it lies completely within the pharynx. When one is swallowing it serves as part of the anterior of the larynx.
In some languages, the epiglottis is used to produce speech sounds, though this sound-type is rather rare. Further information can be found under epiglottal consonant
.
. The epiglottis has two surfaces, a lingual and a laryngeal surface, related to the oral cavity and the larynx
respectively.
secreting Goblet cells.
(CN IX) sends fibers to the upper epiglottis that contribute to the afferent
limb of the gag reflex
. The superior laryngeal branch of the vagus nerve
(CN X) sends fibers to the lower epiglottis that contribute to the efferent limb of the cough reflex
.
and Streptococci in the trachea, causing massive inflammation, called "Epiglottitis
". This condition has become rare in countries where vaccination
against Haemophilus influenzae (Hib) is administered.
Elastic cartilage
Elastic cartilage or yellow cartilage is a type of cartilage present in the outer ear, larynx, and epiglottis. It contains elastic fiber networks and collagen fibers. The principal protein is elastin....
tissue covered with a mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...
, attached to the entrance of the larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. The term, like tonsil
Tonsil
Palatine tonsils, occasionally called the faucial tonsils, are the tonsils that can be seen on the left and right sides at the back of the throat....
s, is often incorrectly used to refer to the uvula
Uvula
The palatine uvula, usually referred to as simply the uvula , is the conic projection from the posterior edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers .-Function in language:The uvula plays a role in the...
. There are taste bud
Taste bud
Taste buds contain the receptors for taste. They are located around the small structures on the upper surface of the tongue, soft palate, upper esophagus and epiglottis, which are called papillae. These structures are involved in detecting the five elements of taste perception: salty, sour,...
s on the epiglottis.
Anatomy and function
The epiglottis guards the entrance of the glottisGlottis
The glottis is defined as the combination of the vocal folds and the space in between the folds .-Function:...
, the opening between the vocal folds
Vocal folds
The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx...
.
It is normally pointed upward while one is breathing
Breathing
Breathing is the process that moves air in and out of the lungs. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. Breathing is only one process that delivers oxygen to where it is needed in the body and...
with its underside functioning as part of the pharynx
Pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
, but while one is swallowing
Swallowing
Swallowing, known scientifically as deglutition, is the process in the human or animal body that makes something pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. If this fails and the object goes through the trachea, then choking or pulmonary aspiration...
, elevation of the hyoid bone
Hyoid bone
The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...
draws the larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
upward; as a result, the epiglottis folds down to a more horizontal position, with its superior side functioning as part of the pharynx. In this manner it prevents food from going into the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
and instead directs it to the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
, which is posterior.
The epiglottis is one of nine cartilaginous structures that make up the larynx (voice box). While one is breathing, it lies completely within the pharynx. When one is swallowing it serves as part of the anterior of the larynx.
In some languages, the epiglottis is used to produce speech sounds, though this sound-type is rather rare. Further information can be found under epiglottal consonant
Epiglottal consonant
An epiglottal consonant is a consonant that is articulated with the aryepiglottic folds against the epiglottis. They are occasionally called aryepiglottal consonants.-Epiglottal consonants in the IPA:...
.
Gross appearance
In a cross section of the epiglottis it can be seen that the body consists of elastic cartilageElastic cartilage
Elastic cartilage or yellow cartilage is a type of cartilage present in the outer ear, larynx, and epiglottis. It contains elastic fiber networks and collagen fibers. The principal protein is elastin....
. The epiglottis has two surfaces, a lingual and a laryngeal surface, related to the oral cavity and the larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
respectively.
Mucosa
The entire lingual surface and the apical portion of the laryngeal surface (since it is vulnerable to abrasion due to its relation to the digestive tract) are covered by a stratified squamous non-keratinized epithelium. The rest of the laryngeal surface on the other hand, which is in relation to the respiratory system, has respiratory epithelium: pseudostratified, ciliated columnar cells and mucusMucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
secreting Goblet cells.
Reflexes
The glossopharyngeal nerveGlossopharyngeal nerve
The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve...
(CN IX) sends fibers to the upper epiglottis that contribute to the afferent
Afferent
Afferent is an anatomical term with the following meanings:*Conveying towards a center, for example the afferent arterioles conveying blood towards the Bowman's capsule in the Kidney. Opposite to Efferent.*Something that so conducts, see Afferent nerve fiber...
limb of the gag reflex
Gag reflex
The pharyngeal reflex or gag reflex is a reflex contraction of the back of the throat, evoked by touching the soft palate or sometimes the back of the tongue. It prevents something from entering the throat except as part of normal swallowing and helps prevent choking...
. The superior laryngeal branch of the vagus nerve
Vagus nerve
The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...
(CN X) sends fibers to the lower epiglottis that contribute to the efferent limb of the cough reflex
Cough reflex
The cough reflex has both sensory and motor components. Pulmonary irritant receptors in the epithelium of the respiratory tract are sensitive to both mechanical and chemical stimuli...
.
Infection of the epiglottis
In children, the epiglottis will occasionally become infected with Haemophilus influenzaeHaemophilus influenzae
Haemophilus influenzae, formerly called Pfeiffer's bacillus or Bacillus influenzae, Gram-negative, rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe. H...
and Streptococci in the trachea, causing massive inflammation, called "Epiglottitis
Epiglottitis
Epiglottitis is an inflammation of the epiglottis - the flap that sits at the base of the tongue, which keeps food from going into the trachea . Due to its place in the airway, swelling of this structure can interfere with breathing and constitutes a medical emergency...
". This condition has become rare in countries where vaccination
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
against Haemophilus influenzae (Hib) is administered.
See also
- Epiglottal consonantEpiglottal consonantAn epiglottal consonant is a consonant that is articulated with the aryepiglottic folds against the epiglottis. They are occasionally called aryepiglottal consonants.-Epiglottal consonants in the IPA:...
- Epiglotto-pharyngeal consonantEpiglotto-pharyngeal consonantAn epiglotto-pharyngeal consonant is a newly reported type of consonant, articulated with the epiglottis against the back wall of the pharynx. This contrasts with the pharyngeal consonants, where the root of the tongue contacts the back wall of the pharynx, and prototypical epiglottal consonants,...
- Pharyngeal consonantPharyngeal consonantA pharyngeal consonant is a type of consonant which is articulated with the root of the tongue against the pharynx.-Pharyngeal consonants in the IPA:Pharyngeal consonants in the International Phonetic Alphabet :...