Editing Triquetral bone

{{Short description|Bone in the wrist}}
{{Infobox bone
| Name          = Triquetral bone
| Latin         = os triquetrum, os pyramidale
| Image         = Triangular bone (left hand) 01 palmar view.png
| Caption       = Left hand anterior view (palmar view). Triquetral bone shown in red.
| Image2        = Gray223.png
| Caption2      = The left triquetal bone
| Origins       =
| Insertions    =
| Articulations = Articulates with ''three'' bones:<br>[[Lunate bone|lunate]] laterally<br>[[pisiform]] in front<br>[[hamate]] distally<br>triangular [[articular disk]] which separates it from the lower end of the [[ulna]].
}}
The '''triquetral bone''' ({{IPAc-en|t|r|ai|'|k|w|E|t|r|@l|,_|-|'|k|w|i:|-}}; also called '''triquetrum''', '''pyramidal''', '''three-faced''', and formerly '''cuneiform''' bone) is located in the [[wrist]] on the medial side of the proximal row of the [[Carpal bones|carpus]] between the [[Lunate bone|lunate]] and [[pisiform bone|pisiform]] bones. It is on the [[ulna]]r side of the hand, but does not directly articulate with the [[ulna]]. Instead, it is connected to and articulates with the ulna through the [[Triangular fibrocartilage]] disc<ref name="Manaster">Manaster, B. J., Julia Crim "Imaging Anatomy: Musculoskeletal E-Book" Elsevier Health Sciences, 2016, p. 326.</ref> and ligament, which forms part of the ulnocarpal joint capsule.<ref>{{cite web |url=https://radiopaedia.org/articles/ulnotriquetral-ligament?lang=us |title=Ulnotriquetral ligament |last=Feger |first=Joachim |website=radiopedia.org |access-date=September 28, 2022}}</ref> It connects with the [[pisiform bone|pisiform]], [[Hamate bone|hamate]], and [[Lunate bone|lunate]] bones. It is the 2nd most commonly fractured carpal bone.

==Structure==
The triquetral is one of the eight [[carpal bone]]s of the [[hand]]. It is a three-faced bone found within the proximal row of carpal bones. Situated beneath the [[pisiform bone|pisiform]], it is one of the carpal bones that form the carpal arch, within which lies the [[carpal tunnel]]. 
<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}}

The triquetral bone may be distinguished by its pyramidal shape, and by an oval isolated facet for articulation with the pisiform bone. It is situated at the upper and ulnar side of the carpus. To facilitate its palpation in an exam, the hand must be radially deviated so that the triquetrium moves out from under the ulnar styloid process. The triquetrum may be difficult to find, since it also lies under the pisiform.

The triquetral bone has nutrient foramina for entering the nutrient vessels into the bone which comes from branches of the radial, ulnar, and interosseous arteries.<ref>{{cite journal |last1=balci |first1=aybegum |title=The morphologic and morphometric features of the triquetrum |journal=Hand Surgery and Rehabilitation |date=1 November 2022 |volume=42 |issue=1 |pages=40–44 |doi=10.1016/j.hansur.2022.11.002}}</ref>

==Ossification==
The triquetral bone ossifies between 9 months and 50 months (4 years and 2 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>

===Surfaces===
The ''superior surface'' presents a medial, rough, non-articular portion, and a lateral convex articular portion which articulates with the triangular articular disk of the wrist.

The ''inferior surface'', directed lateralward, is concave, sinuously curved, and smooth for articulation with the hamate. The dorsal surface is rough for the attachment of ligaments.

The ''volar surface'' presents, on its medial part, an oval facet, for articulation with the pisiform; its lateral part is rough for ligamentous attachment.

The ''lateral surface'', the base of the pyramid, is marked by a flat, quadrilateral facet, for articulation with the lunate.

The ''medial surface'', the summit of the pyramid, is pointed and roughened, for the attachment of the ulnar collateral ligament of the wrist.

===In animals===
In reptiles and amphibians, the bone is instead referred to as the ''ulnare'', since (at least in the most primitive fossils) it articulates with the [[ulna]].

==Function==
The carpal bones function as a unit to provide a bony superstructure for the [[hand]].<ref name=GRAYS2005 /> {{rp|708}}

==Fracture==
Triquetral fractures can occur due to forceful flexion of the wrist, causing an [[avulsion fracture|avulsion]] of the [[Dorsum (anatomy)|dorsal]] aspect of the bone that is often hidden on anterior radiographs, but can be seen as a tiny bone fragment on [[lateral (anatomy)|lateral]] views.

==Etymology==
The etymology derives from the Latin ''triquetrus'' which means "three-cornered." Therefore, it is sometimes also called the '''triangular bone''' or '''os triangulare'''. However, ''os triangulare'' may also refer to a nearby [[Accessory bone#Wrist and hand|accessory bone]].

==Additional images==
<gallery>
 File:Triangular bone (left hand) - animation01.gif|Triquetral bone of the left hand (shown in red). Animation.
 File:Triangular bone (left hand) - animation02.gif|Triquetral bone of the left hand. Close up. Animation.
 File:Triquetral bone.jpg|Triquetral bone.
 File:RightHumanPosteriorDistalRadiusUlnaCarpals - Triquetral bone.png|Right hand posterior view (dorsal view). Thumb on bottom.
 File:RightHumanAnteriorDistalRadiusUlnaCarpals - Triquetral bone.png|Right hand anterior view (palmar view). Thumb on top.
 File:Gray219 - Triangular bone.png|Bones of the left hand. Palmar surface. Triquetral shown in yellow.
 File:Gray220- Triangular bone.png|Bones of the left hand. Dorsal surface. Triquetral shown in yellow.
 File:Ospoignet - Triquetral bone.png|Cross section of wrist (thumb on left). Triquetral shown in red.
 File:Dorsale Triquetrumabsprengung - CT VRT with arrow.png|Triquetral fracture indicated by the white arrow.
 File:TriQFracture.PNG|Triquetral fracture as seen on lateral view of a radiograph.
</gallery>

== References ==
{{Reflist}}

== See also ==
{{Commons}}
{{Anatomy-terms}}
*[[Pisiform bone]]

{{Bones of upper extremity}}
{{Authority control}}

{{DEFAULTSORT:Triquetral Bone}}
[[Category:Skeletal system]]
[[Category:Wrist]]
[[Category:Bones of the hand]]
[[Category:Carpal bones]]