Ans. d. Radial nerve injury The patients who are not able to extend the wrist, unable to make a strong hand grip and if there is loss of sensation on dorsum of hand and fingers, it is suggestive of Radial nerve injury.WRIST-DROPDue to palsy of Extensor carpi radialis longus and brevis, Extensor carpi ulnaris.Radial Nerve InjuryRadial nerve injury rarely occurs at sites other than humeral shaft or the posterior third of the dorsoradial forearmQ.Injuries to the radial nerve at this high level typically do not affect triceps function and elbow extensors are preservedQ. However, predictable motor paralysis results in loss of wrist extension in addition to thumb extension and abduction, finger metacarpophalyngeal joint extension0. Wrist extension is necessary for proper flexor tendon tensioning and hence, grip is profoundly reduced and represents the most imopratnt functional deficit after high radial nerve palsy0.Radial Nerve InjuryObservation is indicated in most nerve palsies associated with closed humeral fractureMotor DeficitsWrist dropdeg: Due to palsy of Extensor carpi radialis longus and brevis, Extensor carpi ulnarisDifficulty in making a fistdeg: Due to loss of synergy between wrist extensors and finger flexorsSensory DeficitsSensory deficit in posterior lateral arm and dorsum of handdeg