In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: symphysis menti) or line of junction where the two lateral halves of the mandible typically fuse in the first year of life (6–9 months after birth).[1] It is not a true symphysis as there is no cartilage between the two sides of the mandible.
Mandibular symphysis
Anterior view of mandible, showing mandibular symphysis (red broken line)
Medial surface of the left half of the mandible, dis-articulated from the right side at the mandibular symphysis
This ridge divides below and encloses a triangular eminence, the mental protuberance, the base of which is depressed in the center but raised on either side to form the mental tubercle. The lowest (most inferior) end of the mandibular symphysis — the point of the chin — is called the "menton".[2][3]
Solitary mammalian carnivores that rely on a powerful canine bite to subdue their prey have a strong mandibular symphysis, while pack hunters delivering shallow bites have a weaker one.[4] When filter feeding, the baleen whales, of the suborder Mysticeti, can dynamically expand their oral cavity in order to accommodate enormous volumes of sea water. This is made possible thanks to its mandibular skull joints, especially the elastic mandibular symphysis which permits both dentaries to be rotated independently in two planes. This flexible jaw, which made the titanic body sizes of baleen whales possible, is not present in early whales and most likely evolved within Mysticeti.[5]
Many primitive proboscideans belonging to the group Elephantiformes have a greatly elongated mandibular symphysis. This was lost in many later groups, including modern elephants.[6]
Referencesedit
This article incorporates text in the public domain from page 172 of the 20th edition ofGray's Anatomy(1918)
Notesedit
^Becker, Marshall Joseph (Apr 1986). "Mandibular symphysis (medial suture) closure in modern Homo sapiens: Preliminary evidence from archaeological populations". American Journal of Physical Anthropology. 69 (4): 499–501. doi:10.1002/ajpa.1330690409. ISSN 0002-9483. Retrieved 2023-12-10.
^"Menton". The Free Dictionary. Retrieved 1 November 2016.
^Phulari, Basavaraj Subhashchandra (2013). An atlas on cephalometric landmarks (1st ed.). New Delhi: Jaypee Brothers Medical Publishers. p. 174. ISBN9789350903247.
^Therrien, François (2005). "Mandibular force profiles of extant carnivorans and implications for the feeding behaviour of extinct predators". Journal of Zoology. 267 (3): 249. doi:10.1017/S0952836905007430.
^Li, Chunxiao; Deng, Tao; Wang, Yang; Sun, Fajun; Wolff, Burt; Jiangzuo, Qigao; Ma, Jiao; Xing, Luda; Fu, Jiao (2023-08-16). Longer mandible or nose? Co-evolution of feeding organs in early elephantiforms (Report). Paleontology. doi:10.1101/2023.08.15.553347.
Sourcesedit
Fitzgerald, Erich M. G. (2012). "Archaeocete-like jaws in a baleen whale". Biol. Lett. 8 (1): 94–96. doi:10.1098/rsbl.2011.0690. PMC3259978. PMID 21849306.
mandibular, symphysis, human, anatomy, facial, skeleton, skull, external, surface, mandible, marked, median, line, faint, ridge, indicating, mandibular, symphysis, latin, symphysis, menti, line, junction, where, lateral, halves, mandible, typically, fuse, firs. In human anatomy the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge indicating the mandibular symphysis Latin symphysis menti or line of junction where the two lateral halves of the mandible typically fuse in the first year of life 6 9 months after birth 1 It is not a true symphysis as there is no cartilage between the two sides of the mandible Mandibular symphysisAnterior view of mandible showing mandibular symphysis red broken line Medial surface of the left half of the mandible dis articulated from the right side at the mandibular symphysisDetailsIdentifiersLatinsymphysis mandibulaeTA98A02 1 15 004TA2838FMA75779Anatomical terms of bone edit on Wikidata This ridge divides below and encloses a triangular eminence the mental protuberance the base of which is depressed in the center but raised on either side to form the mental tubercle The lowest most inferior end of the mandibular symphysis the point of the chin is called the menton 2 3 It serves as the origin for the geniohyoid and the genioglossus muscles Contents 1 Other animals 2 References 2 1 Notes 2 2 SourcesOther animals edit nbsp Humpback skeleton showing the flexible slingshot symphysis present in baleen whales nbsp Skull and jaws of the tetralophodont gomphothere Tetralophodon longirostris a proboscidean demonstrating mandibular symphysis elongation Solitary mammalian carnivores that rely on a powerful canine bite to subdue their prey have a strong mandibular symphysis while pack hunters delivering shallow bites have a weaker one 4 When filter feeding the baleen whales of the suborder Mysticeti can dynamically expand their oral cavity in order to accommodate enormous volumes of sea water This is made possible thanks to its mandibular skull joints especially the elastic mandibular symphysis which permits both dentaries to be rotated independently in two planes This flexible jaw which made the titanic body sizes of baleen whales possible is not present in early whales and most likely evolved within Mysticeti 5 Many primitive proboscideans belonging to the group Elephantiformes have a greatly elongated mandibular symphysis This was lost in many later groups including modern elephants 6 References edit nbsp This article incorporates text in the public domain from page 172 of the 20th edition of Gray s Anatomy 1918 Notes edit Becker Marshall Joseph Apr 1986 Mandibular symphysis medial suture closure in modern Homo sapiens Preliminary evidence from archaeological populations American Journal of Physical Anthropology 69 4 499 501 doi 10 1002 ajpa 1330690409 ISSN 0002 9483 Retrieved 2023 12 10 Menton The Free Dictionary Retrieved 1 November 2016 Phulari Basavaraj Subhashchandra 2013 An atlas on cephalometric landmarks 1st ed New Delhi Jaypee Brothers Medical Publishers p 174 ISBN 9789350903247 Therrien Francois 2005 Mandibular force profiles of extant carnivorans and implications for the feeding behaviour of extinct predators Journal of Zoology 267 3 249 doi 10 1017 S0952836905007430 Fitzgerald 2012 Li Chunxiao Deng Tao Wang Yang Sun Fajun Wolff Burt Jiangzuo Qigao Ma Jiao Xing Luda Fu Jiao 2023 08 16 Longer mandible or nose Co evolution of feeding organs in early elephantiforms Report Paleontology doi 10 1101 2023 08 15 553347 Sources edit Fitzgerald Erich M G 2012 Archaeocete like jaws in a baleen whale Biol Lett 8 1 94 96 doi 10 1098 rsbl 2011 0690 PMC 3259978 PMID 21849306 Portal nbsp Anatomy nbsp This human musculoskeletal system article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Mandibular symphysis amp oldid 1189262396, wikipedia, wiki, book, books, library,
