|Origin||Lateral epicondyle of the humerus.|
|Insertion||Dorsal surface of the four fingers.|
|Action||Straightens and pulls back the fingers.|
The axis of extensor digitorum goes from the lateral epicondyle to the middle of the dorsal side of the wrist. When tensed, the belly is visible on the upper half of the arm. The deep ridges on the upper end of a muscular forearm are often on either side of extensor digitorum.