Rosh Emergency Medicine Practice Test

Which physical exam finding should raise suspicion for the most likely associated nerve injury in a patient who fell on an outstretched arm?

1. Inability to abduct fingers

2. Inability to extend the wrist

3. Inability to flex the wrist

4. Inability to make an OK sign

The correct answer is: Inability to extend the wrist

The physical exam finding of inability to extend the wrist should raise suspicion for a radial nerve injury, which is commonly associated with falls on an outstretched arm. This type of fall often leads to injury of the radial nerve as it passes around the humeral shaft. The characteristic result of a radial nerve injury is wrist drop, where the patient cannot extend the wrist or fingers, resulting in a loss of functional use of the hand. Recognizing this finding is crucial because it points towards a specific neurological deficit that can help guide further evaluation and management. A thorough understanding of the anatomy and mechanics involved in injuries or impingements will assist clinicians in identifying potential nerve damage based on physical exam findings. The other options represent different nerve injuries — the ability to abduct fingers relates to the ulnar and median nerves, the inability to flex the wrist could suggest median or ulnar nerve issues, and the inability to make an OK sign points to median nerve impairment — but in the context of an outstretched arm injury, the loss of wrist extension is distinctively indicative of a radial nerve injury.