The extensor group of muscles occupies the posterior surface and lateral (outer) border of the forearm.
Origin
The extensor carpi ulnaris originates on the lateral condyle of the humerus.
Insertion
It inserts on the fifth metacarpal bone of the hand.
Function
Extension and adduction (ulna flexion) of the wrist. It is involved in wrist joint extension and stabilization and possibly assists in extension of the elbow.