Physiology A 4-year-old boy fell on outstretched hand. X- ray is shown below. Which blood vessel is most commonly affected? A Ulnar artery B Radial artery C Brachial artery D Cubital vein 💡 Explanation A 4-year-old boy fell on outstretched hand. X- ray is shown below. Which blood vessel is most commonly affected? ✓ Correct Answer: C. Brachial artery