A. Radial groove: The radial (spiral) groove runs along the mid-shaft of the humerus and houses the radial nerve — injury here commonly causes wrist drop and sensory loss on the posterior forearm/hand. B. Greater tubercle: The greater tubercle is on the proximal humerus and is the site for rotator cuff muscle attachments; it’s not the landmark for mid-shaft nerve injury. C. Coracoid process: Part of the scapula (anterior shoulder), important for muscle/ligament attachment, not adjacent to the humeral mid-shaft or the radial nerve. D. Medial epicondyle: A distal humeral landmark near the elbow where the ulnar nerve passes (cubital tunnel) — relevant to elbow/ulnar nerve injury, not mid-shaft radial nerve injury.