|Posterior view of the larynx. The epiglottis is the most superior structure shown.|
|Gray's||subject #236 1075|
|Precursor||Hypobranchial eminence[unreliable source?]|
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. There are taste buds on the epiglottis.
Anatomy and function
The epiglottis guards the entrance of the glottis, 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 larynx. When one is swallowing it serves as part of the anterior of the pharynx.
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.
In a direct section of the epiglottis it can be seen that the body consists of elastic cartilage. The epiglottis has two surfaces, a lingual and a laryngeal surface, related to the oral cavity and the larynx respectively.
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 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 mucus secreting Goblet cells.
The glossopharyngeal nerve (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.
Infection of the epiglottis
In children, the epiglottis will occasionally become infected with Haemophilus influenzae 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.
- Stevenson, Roger E. (2006). Human malformations and related anomalies. Oxford [Oxfordshire]: Oxford University Press. ISBN 0-19-516568-3.
- Jowett, Shrestha, 1998. Mucosa and taste buds of the human epiglottis. Journal of Anatomy 193(Pt 4): 617–618. [Link]
- April, Ernest. Clinical Anatomy, 3rd ed. Lippincott, Williams, and Wilkins.