Flex Your Knowledge: Conquer the 2026 Muscular System Anatomy & Physiology Test!

Extension is the movement that increases the angle between the two bones at a joint, straightening the limb. It moves from a bent (flexed) position toward a more extended one, often toward straight alignment. This is the opposite of flexion, which decreases the angle. For example, straightening the elbow or knee increases the joint angle. Circumduction involves a circular path made by combining several movements, not just extending, and rotation is turning a bone around its long axis, which changes orientation rather than simply increasing joint angle.