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Hyoid bone

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Hyoid
Thehyoid bone,present at the front of the neck, has a body and two sets of horns
Details
PrecursorSecond and thirdbranchial arch[1]
Identifiers
Latinos hyoideum
MeSHD006928
TA98A02.1.16.001
TA2876
FMA52749
Anatomical terms of bone

Thehyoid bone(lingual boneortongue-bone) (/ˈhɔɪd/[2][3]) is ahorseshoe-shapedbonesituated in the anterior midline of theneckbetween thechinand thethyroid cartilage.At rest, it lies between the base of themandibleand the thirdcervical vertebra.

Unlike other bones, the hyoid is only distantlyarticulatedto other bones by muscles or ligaments. It is the only bone in the human body that is not connected to any other bones. The hyoid is anchored by muscles from the anterior, posterior and inferior directions, and aids in tongue movement and swallowing. The hyoid bone provides attachment to the muscles of thefloor of the mouthand the tongue above, thelarynxbelow, and theepiglottisandpharynxbehind.[citation needed]

Its name is derived fromGreekhyoeides'shaped like the letterupsilon(υ)'.[4][5]

Structure

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Left:Position of hyoid bone (shown in red).Right:Shape of hyoid bone.

The hyoid bone is classed as anirregular boneand consists of a central part called the body, and two pairs of horns, the greater and lesser horns.

Body

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The body of the hyoid bone is the central part of the hyoid bone.[clarification needed]

  • At the front, the body is convex and directed forward and upward.
  • It is crossed in its upper half by a well-marked transverse ridge with a slight downward convexity, and in many cases a vertical median ridge divides it into two lateral halves.
  • The portion of the vertical ridge above the transverse line is present in a majority of specimens, but the lower portion is evident only in rare cases.[clarification needed]
  • The anterior surface gives insertion to thegeniohyoid musclein the greater part of its extent both above and below the transverse ridge; a portion of the origin of thehyoglossusnotches the lateral margin of the geniohyoid attachment.
  • Below the transverse ridge themylohyoid,sternohyoid,andomohyoidare inserted.
  • At the back, the smooth, concave, directed backward and downward, and separated from theepiglottisby thehyothyroid membraneand a quantity ofloose areolar tissue;abursaintervenes between it and the hyothyroid membrane.
  • Above, the body is rounded, and gives attachment to the hyothyroid membrane and someaponeuroticfibers of thegenioglossus.
  • Below, the body affords insertion medially to the sternohyoid and laterally to the omohyoid and occasionally a portion of thethyrohyoid.It also gives attachment to the Levator glandulae thyreoideae, when this muscle is present.

Horns

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The lesser and greater horns of the hyoid

The greater and lesser horns (Latin:cornua) are two sections of bone that project from each side of the hyoid.

Greater horns

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The greater horns project backward from the outer borders of the body; they are flattened from above downward and taper to their end, which is a bonytubercleconnecting to thelateral thyrohyoid ligament.The upper surface of the greater horns are rough and close to its lateral border, and facilitates muscular attachment. The largest of muscles that attach to the upper surface of the greater horns are thehyoglossusand themiddle pharyngeal constrictor,which extend along the whole length of the horns; thedigastric muscleandstylohyoid musclehave small insertions in front of these near the junction of the body with the horns. To the medial border, thethyrohyoid membraneis attached, while the anterior half of the lateral border gives insertion to thethyrohyoid muscle.[citation needed]

Lesser horns

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The lesser horns are two small, conical eminences, attached by their bases to the angles of junction between the body and greater horns of the hyoid bone. They are connected to the body of the bone by fibrous tissue, and occasionally to the greater horns by distinct diarthrodialjoints,which usually persist throughout life, but occasionally becomeankylosed.The lesser horns are situated in the line of the transverse ridge on the body and appear to be continuations of it. The apex of each horn gives attachment to thestylohyoid ligament;thechondroglossusrises from the medial side of the base.[citation needed]

Development

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The secondpharyngeal arch,also called the hyoid arch, gives rise to the lesser cornu of the hyoid and the upper part of the body of the hyoid. The cartilage of the third pharyngeal arch forms the greater cornu of the hyoid and the lower portion of the body of the hyoid.

The hyoid isossifiedfrom six centers: two for the body, and one for each cornu. Ossification commences in the greater cornua toward the end offetal development,in the hyoid body shortly afterward, and in the lesser cornua during the first or second year after birth. Until middle age, the connection between the body and greater cornu isfibrous.

In early life, the outer borders of the body are connected to the greater horns by synchondroses; after middle life, usually by bony union.

Blood supply

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Blood is supplied to the hyoid bone via thelingual artery,which runs down from thetongueto the greater horns of the bone. The suprahyoid branch of the lingual artery runs along the upper border of the hyoid bone and supplies blood to the attached muscles.

Function

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The hyoid bone sits above thethyroid cartilage.

The hyoid bone is present in manymammals.It allows a wider range of tongue, pharyngeal and laryngeal movements by bracing these structures alongside each other in order to produce variation.[6]Its descent in living creatures is not unique toHomo sapiens,[7]and does not allow the production of a wide range of sounds: with a lower larynx, men do not produce a wider range of sounds than women and two-year-old babies. Moreover, the larynx position of Neanderthals was not a handicap to producing speech sounds.[8]The discovery of a modern-looking hyoid bone of aNeanderthalman in theKebara CaveinIsraelled its discoverers to argue that the Neanderthals had a descendedlarynx,and thus human-likespeechcapabilities.[9]However, other researchers have claimed that the morphology of the hyoid is not indicative of the larynx's position. Recent research has indicated that the hyoid bone may have significant involvement in the ability to swallow. It has been hypothesized that the mammalian hyoid bone evolved in conjunction with the development oflactation,thus allowing babies to suckle milk.[10]It is necessary to take into consideration the skull base, the mandible and the cervical vertebrae and a cranial reference plane.[11][12]

Muscle attachments

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A large number of muscles attach to the hyoid:[13]

Clinical significance

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The hyoid bone is important to a number of physiological functions, including breathing, swallowing and speech. It is also thought to play a key role in keeping the upper airway open during sleep,[14][15]and as such, the development and treatment ofobstructive sleep apnea(OSA; characterized by repetitive collapse of the upper airway during sleep). A mechanistic involvement of the hyoid bone in OSA is supported by numerous studies demonstrating that a more inferiorly positioned hyoid bone is strongly associated with the presence and severity of the disorder.[16][17]Movement of the hyoid bone is also thought to be important in modifying upper airway properties, which was recently demonstrated in computer model simulations.[18]Asurgical procedurethat aims to potentially increase and improve the airway is calledhyoid suspension.

Due to its position, the hyoid bone is not easily susceptible to fracture. In a suspected case of murder or physical abuse of an adult, afractured hyoidstrongly indicates throttling orstrangulation.In children and adolescents (in whom the hyoid bone is still flexible becauseossificationis yet to be completed) fracture may not occur even after serious trauma.

Other animals

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The hyoid bone is derived from the lower half of the secondgill archinfish,which separates the first gill slit from thespiracle,and is often called thehyoid arch.In many vertebrates, it also incorporates elements of other gill arches, and has a correspondingly greater number of cornua.Amphibiansand non-avianreptilesmay have many cornua, while mammals (including humans) have two pairs, andbirdsonly one. In birds, and some reptiles, the body of the hyoid is greatly extended forward, creating a solid bony support for thetongue.[19]The howler monkeyAlouattahas apneumatizedhyoid bone, one of the few cases of postcranial pneumatization of bones outsideSaurischia.

Inwoodpeckers,the hyoid bone is elongated, with the horns wrapping around the back of the skull. This is part of the system that keeps the brain cushioned and undamaged by the pecking action.

Inmammals,the hyoid often determines whether one canroar.If the hyoid is incompletelyossified(for example:lions), it allows the animal to roar, but not purr. If the hyoid is completely ossified (for example:cheetahs), it does not allow the animal to roar, but instead will allow the animal to purr and meow, as seen inhouse cats(lions, cheetahs and house cats all belong to the familyFelidae).[20]

In veterinary anatomy, the termhyoid apparatusis the collective term used to refer to thebonesof thetongue—a pair ofstylohyoidea,a pair ofthyrohyoidea,and unpairedbasihyoideum[21]—and associated, upper-gularconnective tissues.[22]In humans, the single hyoid bone is an equivalent of the hyoid apparatus.[23]

See also

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References

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Public domainThis article incorporates text in thepublic domainfrompage 177of the 20th edition ofGray's Anatomy(1918)

  1. ^hednk-023—Embryo Images atUniversity of North Carolina
  2. ^Oxford English Dictionary2nd edition, 1989.
  3. ^Entry "hyoid"Archived2011-12-29 at theWayback MachineinMerriam-Webster Online DictionaryArchived2017-09-22 at theWayback Machine.
  4. ^Dorland illustrated medical dictionary
  5. ^American heritage dictionary for English language
  6. ^Nishimura, T. (2003)."Descent of the larynx in chimpanzee infants".Proceedings of the National Academy of Sciences.100(12): 6930–6933.Bibcode:2003PNAS..100.6930N.doi:10.1073/pnas.1231107100.PMC165807.PMID12775758.Descent of the larynx in chimpanzee infants
  7. ^Nishimura, T.; et al. (2006). "Descent of the hyoid in chimpanzees: evolution of face flattening and speech".Journal of Human Evolution.51(3): 244–254.Bibcode:2006JHumE..51..244N.doi:10.1016/j.jhevol.2006.03.005.PMID16730049.
  8. ^Boë, L.J.; et al. (2002). "The potential of Neandertal vowel space was as large as that of modern humans".Journal of Phonetics.30(3): 465–484.doi:10.1006/jpho.2002.0170.
  9. ^Arsenburg, B. et al., A reappraisal of the anatomical basis for speech in middle Paleolithic hominids, in: American Journal of Physiological Anthropology 83 (1990), pp. 137–146.
  10. ^Fitch, Tecumseh W., The evolution of speech: a comparative review, in: Trends in Cognitive Sciences, Vol. 4, No. 7, July 2000 ("Archived copy"(PDF).Archived fromthe original(PDF)on 2007-08-09.Retrieved2007-09-09.{{cite web}}:CS1 maint: archived copy as title (link))
  11. ^Granat; et al. (2006). "Hyoid bone and larynx in Homo. Estimated position by biometrics".Biom. Hum. Et Anthropolol.24(3–4): 243–255.
  12. ^Boë, L.J.; et al. (2006). "Variation and prediction of the hyoid bone position for modern Man and Neanderthal".Biom. Hum. Et Anthropolol.24(3–4): 257–271.
  13. ^Shaw, S. M.; Martino, R. (2013). "The normal swallow: muscular and neurophysiological control".Otolaryngol Clin N Am.46(6): 937–956.doi:10.1016/j.otc.2013.09.006.PMID24262952.
  14. ^Amatoury, J; Kairaitis, K; Wheatley, JR; Bilston, LE; Amis, TC (1 April 2014). "Peripharyngeal tissue deformation and stress distributions in response to caudal tracheal displacement: pivotal influence of the hyoid bone?".Journal of Applied Physiology.116(7): 746–56.doi:10.1152/japplphysiol.01245.2013.PMID24557799.
  15. ^Amatoury, J; Kairaitis, K; Wheatley, JR; Bilston, LE; Amis, TC (1 February 2015). "Peripharyngeal tissue deformation, stress distributions, and hyoid bone movement in response to mandibular advancement".Journal of Applied Physiology.118(3): 282–91.doi:10.1152/japplphysiol.00668.2014.PMID25505028.
  16. ^Sforza, E; Bacon, W; Weiss, T; Thibault, A; Petiau, C; Krieger, J (February 2000). "Upper airway collapsibility and cephalometric variables in patients with obstructive sleep apnea".American Journal of Respiratory and Critical Care Medicine.161(2 Pt 1): 347–52.doi:10.1164/ajrccm.161.2.9810091.PMID10673170.
  17. ^Genta, PR; Schorr, F; Eckert, DJ; Gebrim, E; Kayamori, F; Moriya, HT; Malhotra, A; Lorenzi-Filho, G (1 October 2014)."Upper airway collapsibility is associated with obesity and hyoid position".Sleep.37(10): 1673–8.doi:10.5665/sleep.4078.PMC4173923.PMID25197805.
  18. ^Amatoury, J; Cheng, S; Kairaitis, K; Wheatley, JR; Amis, TC; Bilston, LE (2016)."Development and validation of a computational finite element model of the rabbit upper airway: simulations of mandibular advancement and tracheal displacement".J Appl Physiol.120(7): 743–57.doi:10.1152/japplphysiol.00820.2015.PMID26769952.
  19. ^Romer, Alfred Sherwood; Parsons, Thomas S. (1977).The Vertebrate Body.Philadelphia, PA: Holt-Saunders International. p. 214.ISBN0-03-910284-X.
  20. ^SeaWorldhttps://seaworld.org/animals/all-about/cheetah/communication/
  21. ^Shoshani J., Marchant G.H. (2001.) Hyoid apparatus: a little-known complex of bones and its "contribution" to proboscidean evolution,The World of Elephants - International Congress, Rome,pp. 668–675.
  22. ^Klappenbach, Laura."Hyoid Apparatus - Definition of Hyoid Apparatus".The New York Times Company.Archived fromthe originalon 2012-01-20.Retrieved2017-03-20.
  23. ^"hyoid apparatus - Definition".mondofacto.com.Archivedfrom the original on 2011-11-08.
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