What actions are performed by the extensor carpi ulnaris?

The correct action of the extensor carpi ulnaris is extension and adduction of the wrist. This muscle is one of the key muscles acting on the wrist joint located on the posterior aspect of the forearm. It arises from the lateral epicondyle of the humerus and its tendon runs along the ulnar side of the wrist.

When the extensor carpi ulnaris contracts, it facilitates the extension movement of the wrist, increasing the angle between the dorsal side of the hand and the forearm. Additionally, it contributes to the adduction (or ulnar deviation) of the wrist, pulling the hand towards the ulnar side (the side of the little finger). This dual action is particularly significant in activities that require precision and stability of the wrist during grasping or manipulation tasks.

Understanding this muscle's function is crucial for diagnosing and treating wrist and forearm conditions, as well as for designing orthotic devices that may either assist or limit these specific movements based on patient needs.