The act of decreasing the angle between the long bones.

• A. Extension
• B. Flexion
• C. Abduction
• D. Adduction

Answer: (B)

Flexion is the movement that decreases the angle between two long bones. When a joint bends, the bones move closer together, so the angle at the joint gets smaller—think of bending the elbow or knee. Extension is the opposite, straightening the joint to increase that angle. Abduction and adduction involve moving a limb away from or toward the body's midline, respectively, and do not describe the action of reducing the inter-bone angle at a hinge joint.