Final answer:
Radial/ulnar nerve damage in the supine position can occur from distal humerus fractures resulting from falls or direct blows to the elbow that cause swelling and compression of these nerves.
Step-by-step explanation:
Radial and ulnar nerve damage might occur in the supine position due to various injuries, particularly those affecting the arms. One common cause is a distal humerus fracture, which can happen from a fall onto the tip of the elbow. This type of fracture often involves the olecranon of the ulna being driven upward, creating a supracondylar fracture or separating one or both of the epicondyles from the body of the humerus, known as an intercondylar fracture. Such injuries can lead to compression of nearby nerves, including the radial and ulnar nerves, due to swelling in surrounding tissues.