Editing Upper limb (section)

====Wrist====
{{Main|Wrist}}
The [[wrist]] ({{langx|la|carpus}}),<ref name="Thieme-Atlas-208" /> composed of the [[carpal bones]], articulates at the wrist joint (or [[radiocarpal joint]]) proximally and the [[carpometacarpal joint]] distally.  The wrist can be divided into two components separated by the [[midcarpal joint]]s.  The small movements of the eight carpal bones during composite movements at the wrist are complex to describe, but flexion mainly occurs in the midcarpal joint whilst extension mainly occurs in the radiocarpal joint; the latter joint also providing most of adduction and abduction at the wrist.
<ref name="Sellers-8">{{harvnb|Sellers|2002| pp=8–9}}</ref>
[[File:3D Medical Animation Human Wrist.jpg|alt=3D Medical Animation still shot of Human Wrist|thumb|228x228px|3D medical animation still shot of human wrist]]
How muscles act on the wrist is complex to describe.  The five muscles acting on the wrist directly&nbsp;— [[flexor carpi radialis]], [[flexor carpi ulnaris]], [[extensor carpi radialis longus muscle|extensor carpi radialis]], [[extensor carpi ulnaris]], and [[palmaris longus]]&nbsp;— are accompanied by the tendons of the extrinsic hand muscles (i.e. the muscles acting on the fingers).  Thus, every movement at the wrist is the work of a group of muscles; because the four primary wrist muscles (FCR, FCU, ECR, and ECU) are attached to the four corners of the wrist, they also produce a secondary movement (i.e. ulnar or radial deviation).  To produce pure flexion or extension at the wrist, these muscle therefore must act in pairs to cancel out each other's secondary action.  On the other hand, finger movements without the corresponding wrist movements require the wrist muscles to cancel out the contribution from the extrinsic hand muscles at the wrist.
<ref name="Sellers-8" />