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Epiglottis

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Epiglottis
Posterior view of the larynx. The epiglottis is the most superior structure shown.
Latin Epiglottis
Gray's subject #236 1075
System
MeSH A02.165.257.625.411
[[Image:|190px|center|]]

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 tonsils, is often incorrectly used to refer to the uvula.[1] There are taste buds on the epiglottis.[2]

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 pharynx. When one is swallowing it serves as part of the anterior of the larynx.[citation needed]

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.

Histology

Gross appearance

In a cross 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.

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 mucus secreting Goblet cells.

Clinical significance

Reflexes

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.[3]

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.[citation needed]

Additional images

See also

References

  1. [1][dead link]
  2. Jowett, Shrestha, 1998. Mucosa and taste buds of the human epiglottis. Journal of Anatomy 193(Pt 4): 617–618.
  3. April, Ernest. Clinical Anatomy, 3rd ed. Lippincott, Williams, and Wilkins.

External links


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