<prompt> True about peripheral nerve injury in upper limbRadial nerve injury cause anaesthesia over anatomical snuff boxMedian nerve injury cause wrist dropUlnar nerve injury Cause claw handIndex finger anesthesia is caused by median nerve injury  <response>: The radial nerve is very commonly damaged in the region of the radial spiral groove. The common causes of injury are: i intramuscular injections in the arm triceps, ii sleeping in an armchair with the limb hanging by the side of the chair Saturday night palsy, or even the pressure by a crutch crutch paralysis, and iii fractures of the shaft of the humerus. This results in the weakness or loss of power of extension at the wrist wrist drop and sensory loss over a narrow strip on the back of forearm, and on the lateral side of the dorsum of the hand. Ref : B D Chaurasias Human Anatomy , seventh edition , volume 1 , pg. no., 101. 