{{Missing information|the situation in other tetrapods, cf Carpal bone#Other animals|date=March 2025}} {{Short description|Carpal bone in the human hand}} {{Infobox bone | Name = Lunate bone | Latin = os lunatum | Image = RightHandSkeleton.png | Caption = Right hand anterior view (palmar view). Lunate bone shown in red. | Image2 = TwoAspectsOfRightLunate.png | Caption2 = The right lunate bone. (After Gray.) | Origins = | Insertions = | Articulations = Radius proximally<br />capitate and hamate distally<br />scaphoid laterally<br />triquetrum medially<br />triangular fibrocartilage<ref name="Manaster">Manaster, B. J., Julia Crim "Imaging Anatomy: Musculoskeletal E-Book" Elsevier Health Sciences, 2016, p. 326.</ref> }} thumb|Lunate of the right hand on X-ray (labeled L) The '''lunate bone''' ('''semilunar bone''') is a carpal bone in the human hand. It is distinguished by its deep concavity and crescentic outline. It is situated in the center of the proximal row carpal bones, which lie between the ulna and radius and the hand. The lunate carpal bone is situated between the lateral scaphoid bone and medial triquetral bone.
==Structure== The lunate is a crescent-shaped carpal bone found within the hand. The lunate is found within the proximal row of carpal bones. Proximally, it abuts the radius. Laterally, it articulates with the scaphoid bone, medially with the triquetral bone, and distally with the capitate bone. The lunate also articulates on its distal and medial surface with the hamate bone.<ref name=GRAYS2005>{{cite book|last=Drake|first=Richard L.|title=Gray's anatomy for students|year=2005|publisher=Elsevier/Churchill Livingstone|location=Philadelphia|isbn=978-0-8089-2306-0|author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell |author4=illustrations by Richard |author5= Richardson, Paul }}</ref>{{rp|708}}<ref name=EATHORNE2005 />
The lunate is stabilised by a medial ligament to the scaphoid bone and a lateral ligament to the triquetral bone. Ligaments between the radius and carpal bone also stabilise the position of the lunate, as does its position in the lunate fossa of the radius.<ref name=EATHORNE2005 />
===Bone=== The proximal surface of the lunate bone is smooth and convex, articulating with the radius. The lateral surface is flat and narrow, with a crescentic facet for articulation with the scaphoid bone. The medial surface possesses a smooth and quadrilateral facet for articulation with the triquetral bone. The palmar surface is rough, as is the dorsal surface. The dorsal surface is broad and rounded. The distal surface of the bone is deep and concave.<ref name=GRAYS1918>{{cite book|last=Gray|first=Henry|title=Anatomy of the Human Body|year=1918|page=6b. The Hand. 1. The Carpus|url=http://www.bartleby.com/107/54.html|access-date=5 January 2014}}</ref>
===Blood supply=== The lunate receives its blood supply from dorsal and palmar branches.<ref name=EATHORNE2005 />
===Variation=== The lunate has a variable shape. About one-third of lunate bones do not possess a medial facet, meaning they do not articulate with the hamate bone. Additionally, in about 20% of people, blood supply may arise from palmar vessels alone.<ref name=EATHORNE2005 />
===Ossification=== The ossification of the lunate bone commences between 18 months and 4 years 3 months.<ref name=CHLT>{{cite journal|last1=Balachandran|first1=Ajay|last2=Kartha|first2=Moumitha|last3=Krishna|first3=Anooj|last4=Thomas|first4=Jerry|last5=K|first5=Prathilash|last6=TN|first6=Prem|last7=GK|first7=Libu|last8=B|first8=Krishnan|last9=John|first9=Liza|title=A Study of Ossification of Capitate, Hamate, Triquetral & Lunate in Forensic Age Estimation|journal=Indian Journal of Forensic Medicine & Toxicology|date=2014|volume=8|issue=2|pages=218–224|doi=10.5958/0973-9130.2014.00720.8|url=http://www.indianjournals.com/ijor.aspx?target=ijor:ijfmt&volume=8&issue=2&article=052|access-date=18 August 2014|issn=0973-9130|url-access=subscription}}</ref>
==Function== The carpal bones function as a unit to provide a bony superstructure for the hand.<ref name=GRAYS2005 />{{rp|708}} As a proximal carpal bone, the lunate is also involved in movement of the wrist.<ref name=EATHORNE2005>{{cite journal|last=Eathorne|first=SW|title=The wrist: clinical anatomy and physical examination--an update.|journal=Primary Care|date=Mar 2005|volume=32|issue=1|pages=17–33|pmid=15831311|doi=10.1016/j.pop.2004.11.009}}</ref>
== Clinical relevance == thumb|Perilunar dislocation as seen on X-ray (right upper limb). The lunate bone is the most frequently dislocated carpal bone. For its diagnosis, a little-known depression on the dorsal aspect of the wrist, known as the ''lunate foveola,'' is used.<ref>{{Cite journal |last=Wozniak |first=Slawomir |last2=Paulsen |first2=Friedrich |date=October 2023 |title=Introducing the Foveola lunata, an anatomical landmark of the wrist |url=https://linkinghub.elsevier.com/retrieve/pii/S0940960223001188 |journal=Annals of Anatomy - Anatomischer Anzeiger |language=en |volume=250 |article-number=152163 |doi=10.1016/j.aanat.2023.152163|url-access=subscription }}</ref> <!--from http://www.wheelessonline.com/ortho/lunate --> *Carpal coalition *Kienbock's disease *Teisen classification
==Etymology== The name of the lunate bone derives from the "crescent-shaped" ({{langx|la|lunatus}}),<ref>{{cite web|last=Harper|first=Douglas|title=Lunate|url=http://www.etymonline.com/index.php?allowed_in_frame=0&search=lunate&searchmode=none|work=Online Etymology Dictionary|access-date=5 January 2014}}</ref> from Latin ''luna'' ("moon"), from the bone's resemblance to a crescent moon. In amphibians and reptiles, the bone is instead referred to as the '''''intermedium''''', because of its position between the other two proximal carpals.
==Additional images== <gallery> File:Lunate bone (left hand) - animation01.gif|Lunate bone of the left hand (shown in red). Animation. File:Lunate bone (left hand) - animation02.gif|Lunate bone of the left hand. Close up. Animation. Image:Lunate bone.jpg|Lunate bone. Image:Gray219 - Lunate bone.png|Bones of the left hand. Volar surface. Image:Gray220 - Lunate bone.png|Bones of the left hand. Dorsal surface. File:Ospoignet - Lunate bone.png|Cross section of wrist (thumb on left). Lunate shown in red. Image:LunatedislocationAP.jpg|Dislocated lunate Image:LunatedislocationL.jpg|Dislocated lunate File:Dissection of the human hand - 02.jpg|Wrist joint. Deep dissection. Posterior view. File:Slide5kaka.JPG|Wrist joint. Deep dissection. Posterior view. </gallery>
== See also == {{Commons}} {{Anatomy-terms}} * Carpal bone
==References== {{Gray's}} {{reflist}}
{{Bones of upper extremity}}
{{Authority control}}
Category:Wrist Category:Upper limb anatomy Category:Bones of the hand Category:Carpal bones
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