Epiglottis
| Epiglottis | |
|---|---|
 Posterior view of the larynx. The epiglottis is the most superior structure shown. | |
| Details | |
| Precursor | Hypopharyngeal eminence [1][unreliable source?] |
| Identifiers | |
| Latin | Epiglottis |
| MeSH | D004825 |
| TA | A06.2.07.001 |
| FMA | 55130 |
Anatomical terminology [edit on Wikidata] | |
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
3.1 Inflammation
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
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]
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. Gag reflex can be managed by behaviour therapy , cognitive behaviour therapy, herbal remedies, acupressure, acupuncture, prosthetic devices, anti-nausea drugs, sedatives, local or general anaesthetics.[7] Performing dental treatment is challenging in patients who experience gag reflex.
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
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.[8] 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.[9][10]
History
The epiglottis was first described by Aristotle, although the epiglottis' function was first defined by Vesalius in 1543. It also has Greek roots.[11]
Additional images
Epiglotic cartilage.
Larynx
Cut through the larynx of a horse
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
- 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..mw-parser-output cite.citationfont-style:inherit.mw-parser-output qquotes:"""""""'""'".mw-parser-output code.cs1-codecolor:inherit;background:inherit;border:inherit;padding:inherit.mw-parser-output .cs1-lock-free abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-lock-subscription abackground:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registrationcolor:#555.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration spanborder-bottom:1px dotted;cursor:help.mw-parser-output .cs1-hidden-errordisplay:none;font-size:100%.mw-parser-output .cs1-visible-errorfont-size:100%.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-formatfont-size:95%.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-leftpadding-left:0.2em.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-rightpadding-right:0.2em
^ Jowett A, Shrestha R (November 1998). "Mucosa and taste buds of the human epiglottis". J. Anat. 193 ( Pt 4): 617–8. doi:10.1046/j.1469-7580.1998.19340617.x. PMC 1467887. PMID 10029195.
^ abcdef Standring S, Borley NR, eds. (2008). Gray's anatomy : the anatomical basis of clinical practice. Brown JL, Moore LA (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 N, Georgalas C, Bhattacharyya A (2007). "High-rising epiglottis in children: should it cause concern?". J Am Board Fam Med. 20 (5): 495–6. doi:10.3122/jabfm.2007.05.060212. PMID 17823468.
^ Ernest W. April (1997). Nms Clinical Anatomy 3/ed. Lippincott Williams And Wilkins. ISBN 978-81-7431-032-3.
^ Prashanti E, Sumanth KN, Renjith George P, Karanth L, Soe HH (October 2015). "Management of gag reflex for patients undergoing dental treatment". Cochrane Database Syst Rev (10): CD011116. doi:10.1002/14651858.CD011116.pub2. PMID 26423025.
^ 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 BK, Reddy SK, Verghese ST (April 2013). "Acute epiglottitis in the era of post-Haemophilus influenzae type B (HIB) vaccine". J Anesth. 27 (2): 316–7. doi:10.1007/s00540-012-1500-9. PMID 23076559.
^ Hermansen MN, Schmidt JH, Krug AH, Larsen K, Kristensen S (April 2014). "Low incidence of children with acute epiglottis after introduction of vaccination". Dan Med J. 61 (4): A4788. PMID 24814584.
^ Lydiatt DD, Bucher GS (March 2010). "The historical Latin and etymology of selected anatomical terms of the larynx". Clin Anat. 23 (2): 131–44. doi:10.1002/ca.20912. PMID 20069644.
External links
 | Wikimedia Commons has media related to Epiglottis. |
lesson11 at The Anatomy Lesson by Wesley Norman (Georgetown University) (larynxsagsect)
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