Problem: You have a patient who broke her humerus during a mountain bike accident. Many muscles on her arm appear bruised and the injuries look sore and painful, you are glad the patient is sedated and not experiencing any discomfort right now. You and another colleague are prepping the woman for surgery and decide to quiz each other about the humerus - its articulations and attached muscles.
Name the superficial arm muscle involved in elbow flexion. Make clear your understanding of muscle movement by outlining how a muscle's insertion enables actions like this to occur?