Final answer:
Radial nerve damage from a humeral fracture often results in sensory loss in the hand and forearm, wrist drop, and difficulty with arm extension. These signs occur due to nerve compression or direct trauma from the fracture.
Step-by-step explanation:
The signs of radial nerve damage associated with a humeral fracture can be varied but typically include loss of sensation in the back of the hand and forearm, weakness or inability to extend the wrist and fingers (wrist drop), and difficulty in straightening the arm. These symptoms arise because the radial nerve innervates the forearm muscles responsible for these movements and sensations. A fracture of the humerus, particularly at certain locations such as the surgical neck or midshaft, is associated with the risk of radial nerve injury due to the proximity of the nerve to the bone.
If a humeral fracture causes swelling of the surrounding tissues, it could potentially compress related nerves, including the radial nerve. Injuries such as a supracondylar or intercondylar fracture in children could also affect these nerves as a result of a fall on the elbow. Impacted or transverse fractures might cause direct trauma to the nerve.