| Epiglottis |
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Posterior view of the larynx. The epiglottis is the most superior structure shown.
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| Details |
| Precursor |
Hypopharyngeal eminence [1][unreliable source?] |
| Identifiers |
| Latin |
Epiglottis |
| MeSH |
D004825 |
| TA |
A06.2.07.001 |
| FMA |
55130 |
| Anatomical terminology
[edit on Wikidata]
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The epiglottis is a flap in the throat that keeps food from entering the windpipe and the lungs. The flap is made of elastic cartilage 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. It stands open during breathing, allowing air into the larynx. During swallowing, it closes to prevent aspiration, forcing the swallowed liquids or food to go along the esophagus instead. It is thus the valve that diverts passage to either the trachea or the esophagus.
The epiglottis gets its name from being above the glottis (epi- + glottis). There are taste buds on the epiglottis.[2]
Contents
- 1 Structure
- 1.1 Microanatomy
- 1.2 Development
- 1.3 Variation
- 2 Function
- 2.1 Gag reflex
- 2.2 Speech sounds
- 3 Clinical significance
- 4 History
- 5 Additional images
- 6 See also
- 7 References
- 8 External links
Structure
The epiglottis is shaped somewhat like a leaf of purslane, with the stem attached to the internal surface of the thyroid cartilage.[3]
The epiglottis is one of nine cartilaginous structures that make up the larynx (voice box). During breathing, it lies completely within the larynx. During swallowing, it serves as part of the anterior of the pharynx.[citation needed]
Microanatomy
The body of the epiglottis consists of elastic cartilage.
The epiglottis has two surfaces, a forward-facing surface facing the tongue, and a posterior surface facing the larynx.[3]
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)[citation needed] are covered by stratified squamous non-keratinized epithelium.[3] However, some parts of the laryngeal surface, which is in relation to the respiratory system, has respiratory epithelium: pseudostratified, ciliated columnar cells and mucus secreting goblet cells.[3]
Development
The epiglottis arises from the fourth pharyngeal arch. It can be seen as a distinct structure later than the other cartilage of the pharynx, visible around the fifth month of development.[4]
Variation
A high-rising epiglottis is a normal anatomical variation, visible during an oral examination, which does not cause any serious problem apart from a mild sensation of a foreign body in the throat. It is seen more often in children than adults and does not need any medical or surgical intervention.[5][citation needed]
Function
The epiglottis is normally pointed upward during breathing with its underside functioning as part of the pharynx.[3] During 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, the epiglottis prevents food from going into the trachea and instead directs it to the esophagus, which is behind it.[citation needed] Swallowing with little to no aspiration of food can occur even when there is no epiglottis (such as when destroyed by disease).[3]
Gag reflex
Should food or liquid enter the windpipe due to the epiglottis failing to close properly, the gag reflex is induced to protect the respiratory system.[citation needed] The glossopharyngeal nerve sends fibers to the upper epiglottis that contribute to the afferent limb of the gag reflex. (The gag reflex is variable in people from a limited to a hypersensitive response.) The superior laryngeal branch of the vagus nerve sends fibers to the lower epiglottis that contribute to the efferent limb of the cough reflex.[6] This initiates an attempt to try to dislodge the food or liquid from the windpipe.
Speech sounds
In some languages, the epiglottis is used to produce epiglottal consonant speech sounds, though this sound-type is rather rare.
Clinical significance
Inflammation
Main article: Epiglottitis
Inflammation of the epiglottis is known as epiglottitis. Epiglottitis is mainly caused by Haemophilus influenzae. A person with epiglottitis may have a fever, sore throat, difficulty swallowing, and difficulty breathing. For this reason, acute epiglottitis is considered a medical emergency, because of the risk of obstruction of the pharynx. Epiglottitis is often managed with antibiotics, racemic epinephrine (a sympathomimetic bronchodilator that is delivered by aerosol), and may require tracheal intubation or a tracheostomy if breathing is difficult.[7] Behind the root of the tongue is an epiglottic vallecula which is an important anatomical landmark in intubation.
The incidence of epiglottitis has decreased significantly in countries where vaccination against Haemophilus influenzae is administered.[8][9]
History
The epiglottis was first described by Aristotle, although the epiglottis' function was first defined by Vesalius in 1543. It also has Greek roots.[10]
Additional images
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Cut through the larynx of a horse
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Larynx. 1=vocal folds, 2=vestibular fold, 3=epiglottis, 4=plica aryepiglottica, 5=arytenoid cartilage, 6=sinus piriformis, 7=dorsum of the tongue
See also
This article uses anatomical terminology; for an overview, see Anatomical terminology.
- Epiglottal consonant
- Epiglotto-pharyngeal consonant
- Pharyngeal consonant
References
- ^ Stevenson, Roger E. (2006). Human malformations and related anomalies. Oxford [Oxfordshire]: Oxford University Press. ISBN 0-19-516568-3.
- ^ Jowett, A.; Shrestha, R. (1998). "Mucosa and taste buds of the human epiglottis". Journal of Anatomy. 193 (4): 617–618. doi:10.1046/j.1469-7580.1998.19340617.x. PMC 1467887 .
- ^ a b c d e f editor-in-chief, Susan Standring ; section editors, Neil R. Borley; et al. (2008). Gray's anatomy : the anatomical basis of clinical practice (40th ed.). London: Churchill Livingstone. ISBN 978-0-8089-2371-8.
- ^ Schoenwolf, Gary C.; et al. (2009). ""Development of the Urogenital system"". Larsen's human embryology (4th ed., Thoroughly rev. and updated. ed.). Philadelphia: Churchill Livingstone/Elsevier. p. 362. ISBN 9780443068119.
- ^ Petkar, Nadeem; Georgalas, Christos; Bhattacharyya, Abir (September 2007). "High-rising epiglottis in children: should it cause concern?". Journal of the American Board of Family Medicine: JABFM. 20 (5): 495–496. doi:10.3122/jabfm.2007.05.060212. ISSN 1557-2625. PMID 17823468.
- ^ April, Ernest. Clinical Anatomy, 3rd ed. Lippincott, Williams, and Wilkins.
- ^ Nicki R. Colledge; Brian R. Walker; Stuart H. Ralston, eds. (2010). Davidson's principles and practice of medicine. illustrated by Robert Britton (21st ed.). Edinburgh: Churchill Livingstone/Elsevier. p. 681. ISBN 978-0-7020-3084-0.
- ^ Reilly, Brian; Reddy, Srijaya K.; Verghese, Susan T. (Oct 2012). "Acute epiglottitis in the era of post-Haemophilus influenzae type B (HIB) vaccine". Journal of Anesthesia. 27 (2): 316–7. doi:10.1007/s00540-012-1500-9. PMID 23076559. Retrieved Nov 15, 2014.
- ^ Hermansen, MN; Schmidt, J. H.; Krug, A. H.; Larsen, K; Kristensen, S (Apr 2014). "Low incidence of children with acute epiglottis after introduction of vaccination". Dan Med J. 61 (4): A4788. PMID 24814584.
- ^ Lydiatt, Daniel D.; Bucher, Gregory S. (2010). "The historical Latin and etymology of selected anatomical terms of the larynx". Clinical Anatomy: NA. doi:10.1002/ca.20912.
External links
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Wikimedia Commons has media related to Epiglottis. |
- lesson11 at The Anatomy Lesson by Wesley Norman (Georgetown University) (larynxsagsect)
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Anatomy of the larynx
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| Cartilage |
- major/unpaired: Epiglottis
- Thyroid
- Cricoid
- minor/paired: Arytenoid
- Vocal process
- Muscular process
- Corniculate
- Cuneiform
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| Ligaments/folds |
- extrinsic ligaments: Hyoepiglottic ligament
- Thyrohyoid membrane
- Lateral ligament
- Median ligament
- Thyroepiglottic ligament
- Cricotracheal ligament
- intrinsic ligaments, upper: Quadrangular membrane
- Aryepiglottic
- Vestibular ligament/Vestibular fold
- intrinsic ligaments, lower: Cricothyroid ligament
- Median
- Lateral/Conus elasticus
- Vocal ligament/Vocal folds
|
| Laryngeal cavity |
- Laryngeal inlet
- Vestibule
- Rima vestibuli
- Ventricle
- Rima glottidis/Glottis
- Infraglottic cavity
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| Laryngeal muscles |
- Cricothyroid
- Cricoarytenoid
- Arytenoid
- oblique arytenoid
- transverse arytenoid
- Thyroarytenoid
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| Other |
- Cricothyroid articulation
- Cricoarytenoid articulation
|
