If your outer wrist feels sore and achy, you might chalk it up to arthritis. But that discomfort could be ulnar wrist pain, which affects the side of the wrist closest to the pinky finger.

wkes.eu The extensor carpi ulnaris (ECU) muscle plays a key role not only in the active movements of wrist extension and ulnar deviation but also in providing stability to the ulnar side of the wrist.