View source for Pivot joint

{{Short description|Type of joint between bones in the body}}
{{Infobox anatomy
| Name        = Pivot joint
| Latin       = articulatio trochoidea
| Image       = Gelenke_Zeichnung01.jpg
| Caption     = '''1''': [[Ball and socket joint]]; '''2''': [[Condyloid joint]] (Ellipsoid); '''3''': [[Saddle joint]]; '''4''' [[Hinge joint]]; '''5''': Pivot joint;
| Image2      =
| Caption2    =
| Precursor   =
| System      =
}}
In [[animal anatomy]], a '''pivot joint''' ('''trochoid joint''', '''rotary joint''' or '''lateral ginglymus''') is a type of [[synovial joint]] whose [[axis of rotation|movement axis]] is parallel to the [[anatomical terms of location#Axes|long axis]] of the proximal bone, which typically has a convex [[articular surface]].

According to one classification system, a pivot joint like the other [[synovial joint]]—the [[hinge joint]] has one [[degrees of freedom (mechanics)|degree of freedom]].<ref name="Platzer2008p28">Platzer, Werner (2008) ''Color Atlas of Human Anatomy'', Volume 1, [https://books.google.com/books?id=T9bb4T422j8C&pg=PA28 p.28]</ref> Note that the [[degrees of freedom (mechanics)|degrees of freedom]] of a joint is not the same as a joint's [[range of motion]].

==Movements==
Pivot joints allow [[rotation]], which can be external (for example when rotating an arm outward), or internal (as in rotating an arm inward). When rotating the forearm, these movements are typically called [[pronation]] and [[supination]]. In the [[standard anatomical position]], the forearms are supinated, which means that the palms are facing forward, and the thumbs are pointing away from the body. In contrast, a forearm in pronation would have the palm facing backward and the thumb would be closer to the body, pointing medially.

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==Examples==
Examples of a pivot joint include:
* [[Proximal radioulnar joint]]
* [[Distal radioulnar joint]]
* Median [[atlanto-axial joint]]

In contrast, spherical joints (or [[ball and socket joints]]) such as the [[hip joint]] permit rotation and all other directional movement, while pivot joints only permit rotation.

==References==
{{Gray's}}
{{Reflist}}

==External links==
{{Commons category|Pivot joints}}
* [https://web.archive.org/web/20080117043833/http://anatomy.med.umich.edu/modules/joints_module/joints_17.html Synovial Joints-Pivot Joints] from [[University of Michigan Health System|The University of Michigan Medical School]]

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[[Category:Joints]]