This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
[{'content': 'True about peripheral nerve injury in upper limb \nSelect and explain. \nA. Radial nerve injury cause anaesthesia over anatomical snuff box, B. Median nerve injury cause wrist drop, C. Ulnar nerve injury Cause claw hand, D. Index finger anesthesia is caused by median nerve injury', 'role': 'user'}, {'content': "Answer: A \nExplanation: 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 Chaurasia's Human Anatomy , seventh edition , volume 1 , pg. no., 101.", 'role': 'assistant'}]