Athletic Training Practice Exam

A sudden inability to perform wrist extension may indicate what kind of injury?

1. A fracture of the radius

2. A strain of the biceps brachii

3. Radial nerve injury

4. A dislocated shoulder

The correct answer is: Radial nerve injury

The sudden inability to perform wrist extension is closely associated with a radial nerve injury. The radial nerve supplies the muscles responsible for extending the wrist and fingers, so damage to this nerve can result in wrist drop, where the individual is unable to extend the wrist and consequently cannot lift their hand backward. In the case of a radial nerve injury, the patient may retain the ability to flex the wrist and fingers without issue because those movements are primarily controlled by the median and ulnar nerves, which are not affected by a radial nerve injury. Therefore, the inability to extend the wrist serves as a distinct sign suggesting that the radial nerve has been compromised. While a fracture of the radius could potentially result in wrist extension difficulties, the specific inability to extend the wrist points more definitively to a radial nerve injury since it directly affects the muscles involved in that movement. Similarly, a biceps brachii strain would typically not result in an inability to extend the wrist, as the biceps primarily flex the elbow rather than extending the wrist. Lastly, a dislocated shoulder would likely affect shoulder movement more than wrist extension and would not typically lead to this specific symptom. Thus, radial nerve injury is the most accurate interpretation of the symptoms described.