15 year old boy presents to ED due to injurie to his head and right shoulder. His arm is hanging by his side with palm facing posteriorly. He cannont abduct arm has weakness of elbow flexion and diminished sensation over the lateral aspects of the arm and forearm. 1. What sort of injury has he suffered? 2. What muscles are involved?

Your musculoskeletal system includes your bones, cartilage, ligaments, tendons and connective tissues. Your skeleton provides a framework for your muscles and other soft tissues. Together, they support your body's weight, maintain your posture and help you move.