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Wrist Ulnar Deviation

Ulnar deviation occurs in the frontal plane. There is typically more joint range in the ulnar direction. Ulnar deviation is important in positioning the hand but far more important in its use as a power motion as in hammering. The greater range coupled with the fact that the ECU possesses a greater moment arm for ulnar deviation than any other muscle for any other movement of the wrist verifies the importance and power of ulnar deviation.


  • Place the stationary arm on the dorsal mid forearm between radius and ulna
  • Moveable arm is aligned with the third metacarpal
  • It is important not to get distracted by the digits they may deviate in the ulnar direction as the wrist is moved but the moveable arm should stay aligned with the metacarpal not the digits

Strength Testing

While the ulnar deviators can be tested directly, they are more commonly tested with the wrist flexors and extensors. As with the other wrist muscles it is important to look for balance is the person capable of pure wrist ulnar deviation or is an attempt at ulnar deviation accompanied by unwanted wrist flexion or wrist extension. This unwanted movement suggests damage to one of the pair of ulnar deviators. Loss of the dorsal ulnar deviator (ECU) would result in ulnar deviation with wrist flexion. Loss of FCU would result in unwanted wrist extension when trying to purely ulnarly deviate.