Which signs are indicative of radial nerve damage in the context of a humeral fracture?

Radial nerve damage is commonly associated with humeral fractures, particularly in the mid-shaft region of the humerus. The radial nerve responsible for the motor function of the extensor muscles in the posterior compartment of the arm and forearm is at risk of injury during such fractures.

The presence of wrist drop—characterized by the inability to extend the wrist and fingers—is a classic sign of radial nerve injury. This occurs because the extensor muscles are paralyzed, leading to a distinctive clinical picture where the hand is held in a flexed position at the wrist. Additionally, there is a loss of thumb abduction, which is crucial for grasping and gripping motions; this is attributed to the paralysis of the muscles responsible for these actions.

The other signs listed, while they may occur in the context of a humeral fracture or other issues, do not specifically indicate radial nerve injury. Swelling and bruising may be present with any fracture and do not point to nerve damage. Numbness in the forearm could indicate sensory nerve involvement but is not specific enough to suggest radial nerve impairment. Lastly, the inability to flex the elbow is more indicative of injury to the musculocutaneous nerve rather than the radial nerve, as the musculoc