This results from a direct blow to the arm

May injure the radial nerve in the radial groove as it winds around the humeral body, resulting in paralysis of the elbow, wrist, and digit extensors. This causes a “wrist drop”

If the fracture in the humerus occurs, the circumflex nerve and the posterior and anterior circumflex arteries are commonly injured.
- Wrist drop is seen with a lesion of the posterior cord of the brachial plexus.