Wrist drop refers to the inability or severely limited ability to dorsiflex the wrist. Clinically, the hand hangs flaccidly. Wrist drop commonly occurs in association with lesions of the radial nerve.
The more proximal the radial nerve lesion, the more muscle groups are affected. While a distal radial nerve injury generally does not result in wrist drop, injury to the middle portion of the nerve causes the typical wrist drop and a pronated position of the forearm. If the injury is proximal, extension at the elbow joint is also impossible. In wrist drop, grip strength is likewise reduced because paralysis of the extensor muscles leaves the flexor muscles shortened even at rest.