Editing Navicular bone

{{Short description|Small bone found in the feet of most mammals}}
{{For|the bone in the human wrist/hand formerly called navicular|scaphoid bone}}
{{Use dmy dates|date=April 2017}}
{{Infobox bone
| Name          = Navicular bone
| Latin         = os naviculare
| Image         = Foot_bones_-_tarsus,_metatarsus_and_phalanges.jpg
| Caption       = Bones of the human [[foot]], with ''navicularis'' labeled at upper left in image.
| Width         = 300
| Image2        = 
| Caption2      = 
| Articulations =
}}
The '''navicular bone''' {{IPAc-en|n|ə|ˈ|v|ɪ|k|j|ʊ|l|ər}} is a small bone found in the feet of most mammals.

== Human anatomy ==
The navicular bone in humans is one of the [[tarsus (skeleton)|tarsal bones]], found in the [[foot]]. Its name derives from the human bone's resemblance to a small boat, caused by the strongly concave [[Anatomical terms of location#Proximal and distal|proximal]] [[joint|articular surface]]. The term ''navicular bone'' or ''hand navicular bone'' was formerly used for the [[scaphoid bone]],<ref>{{cite web
| url   = http://www.bartleby.com/107/54.html
| title = Gray's Anatomy, 6b. The Hand. 1. The Carpus. 4
| year  = 1918 | access-date = 2018-05-11
}}</ref> one of the [[Carpal bones|carpal bone]]s of the [[wrist]].

The navicular bone in humans is located on the [[Anatomical terms of location#Relative directions|medial]] side of the [[foot]], and articulates proximally with the [[Talus bone|talus]], [[Anatomical terms of location#Relative directions|distally]] with the three [[cuneiform bone]]s, and [[Anatomical terms of location#Relative directions|laterally]] with the [[Cuboid bone|cuboid]].

It is the last of the foot bones to start [[ossification]] and does not tend to do so until the end of the third year in girls and the beginning of the fourth year in boys, although a large range of variation has been reported.<ref>{{cite book
| url   = https://books.google.com/books?id=cYYrHeugqV4C&q=juvenile+skeleton
| title = The Juvenile Skeleton |author1=Louise Scheuer  |author2=Sue Black
 |name-list-style=amp | year  = 2004 
| isbn = 9780080474595 }}</ref>

{{multiple image | direction = horizontal |align=left
 | caption_align = center
 | image1=Slide21DEN.JPG
 | alt1= 
 | caption1=Navicular bone. Superior view.
 | image2=Slide23DEN.JPG
 | alt2=
 | caption2=Navicular bone. Inferior view.
}}
{{Clear}}
[[File:NavicularFracMark.png|thumb|upright|Fracture of the navicular bone]]

The [[Tibialis posterior muscle|tibialis posterior]] is the only muscle that attaches to the navicular bone. The main portion of the muscle inserts into the tuberosity of the navicular bone.<ref name=Bojsen>{{cite book |last1=Bojsen-Møller |first1=Finn  |last2=Simonsen |first2=Erik B. |last3=Tranum-Jensen |first3=Jørgen| year=2001 |title=Bevægeapparatets anatomi |edition=12th |language=da |trans-title=Anatomy of the Locomotive Apparatus | isbn =978-87-628-0307-7|page=293 }}</ref> An [[accessory navicular bone]] may be present in 2–14% of the general population.<ref>{{Cite web|url=https://mdmercy.com/centers-of-excellence/orthopedics-bone-and-joint/institute-for-foot-and-ankle-reconstruction|title=Top Rated Foot Surgeons - Foot & Ankle Institute in Baltimore- Mercy|website=Mercy Medical Center}}</ref><ref>{{Cite web|url=https://www.wheelessonline.com/bones/accessory-navicular/|title=Accessory Navicular|date=2 June 2020}}</ref><ref>{{cite web|url=http://www.macrorad.com/case-reports/symptomatic-accessory-navicular-bone.html|title=Macrorad Teleradiology Case Report - SYMPTOMATIC ACCESSORY NAVICULAR BONE|last=www.mynameiskaan.com}}</ref>

===Clinical significance===
The human navicular is not a commonly broken bone but it breaks due to two reasons. The first mechanism is a stress fracture which happens commonly in athletes,<ref>{{Cite web|url=https://www.nba.com/bucks/news/medical-update-pau-gasol|title=Medical Update On Pau Gasol|website=Milwaukee Bucks|language=en|access-date=2019-12-08}}</ref> and the other mechanism is a high energy trauma.  

The navicular bone is a keystone of the foot: it is part of the coxa pedis and articulates with the talus, first, second and third cuneiform, cuboid and calcaneus. It plays an important role in the biomechanics of the foot, helping in inversion, eversion, and motion; it is a structural link between midfoot and forefoot and it is part of the longitudinal and transverse arch of the foot.

== Horse anatomy ==
{{Main|Navicular syndrome}}
The horse has a [[sesamoid]] bone called the navicular bone, located within the [[horse hoof|hoof]], that lies on the [[Anatomical terms of location#Hands and arms|palmar]] aspect of the [[Equine forelimb anatomy|coffin joint]] between the second [[Phalanx bones|phalanx]] and third phalanx ([[Equine forelimb anatomy#Distal phalanx|coffin bone]]).  The navicular bone in the horse is supported by the distal sesamoidean impar ligament and two collateral sesamoidean ligaments. The navicular bursa is located between the flexor surface of the navicular bone and the deep digital flexor tendon, which runs between the bursa and the distal phalanx.<ref name="Auburn">{{cite web|url=http://www.vetmed.auburn.edu/uploads/7e/32/7e32a4dd9c82d711e57c148824e3b84a/PV1110_waguespack_Surgical.pdf|title=Navicular Syndrome in Equine Patients: Anatomy, Causes, and Diagnosis|author=R. Wayne Waguespack, DVM, MS, DACVS R. Reid Hanson, DVM, DACVS, DACVECC|date=December 2010|work=Surgical Views|publisher=Auburn University|access-date=11 January 2013|url-status=dead|archive-url=https://web.archive.org/web/20121021022902/http://www.vetmed.auburn.edu/uploads/7e/32/7e32a4dd9c82d711e57c148824e3b84a/PV1110_waguespack_Surgical.pdf|archive-date=21 October 2012|df=dmy-all}}</ref>  The central tarsal bone in the [[hock (zoology)|hock]] of the horse is homologous and analogous to the navicular bone of the human foot, and thus the navicular bone in the horse is a different structure from the [[eponymous]]ly labeled bone in humans.<ref>{{Cite web |url=http://cal.vet.upenn.edu/projects/saortho/chapter_32/32mast.htm |title=Chapter 32, FRACTURE AND LUXATION OF THE TARSUS AND METATARSUS "Textbook of Small Animal Orthopaedics" written by Charles D. Newton, D.V.M., M.S. and David M. Nunamaker, V.M.D. J.B. Lippincott Company, 1985. |access-date=11 January 2013 |archive-url=https://web.archive.org/web/20130119014549/http://cal.vet.upenn.edu/projects/saortho/chapter_32/32mast.htm |archive-date=19 January 2013 |url-status=dead }}</ref>
  
The navicular region is an important structure in relation to lameness, particularly in the front feet, and is involved with a significant disease process called navicular disease or navicular syndrome. Recently much of the original literature concerning navicular disease has been called into question, particularly the significance of [[radiographic]] changes as a sole diagnostic criterion.<ref>Citing Clinical Anatomy and Physiology Laboratory Manual for Veterinary Technicians, Colville, Thomas and Bassert, Joanna M. 2008 Publ. Mosby/Elsevier, Canada. "Navicular Bone - The distal sesamoid bone of the horse. The navicular bone is located deep in the hoof behind the joint between the middle and distal phalanges."</ref> Navicular syndrome may be responsible for as much as 1/3 of all cases of lameness in horses, but radiographic changes in the navicular bone do not always provide a definitive diagnosis.  Newer imaging techniques have shown that damage to the soft tissues in the region may be significant contributors to lameness and that multiple causes may result in visible lameness.<ref name="Auburn"/>

== See also ==
*[[Bone#Terminology|Bone terminology]]
*[[Terms for anatomical location]]
*[[Equine forelimb anatomy]]

== Notes ==
{{Reflist}}

==External links==
{{Commons category|Navicular bone}}
* [http://www.embodi3d.com/files/file/80-left-navicular-bone/ 3D printable navicular bone model], free download in STL format (Embodi3D.com)

{{Bones of lower extremity}}
{{Authority control}}

{{DEFAULTSORT:Navicular Bone}}
[[Category:Skeletal system]]
[[Category:Horse anatomy]]
[[Category:Bones of the foot]]
[[Category:Tarsal bones]]