Which joints allow both extension and flexion?

• A. Pivot joints
• B. Hinge joints and ball-and-socket joints
• C. Plane joints
• D. Sutural joints

Answer: (B)

Flexion and extension are movements in the sagittal plane that bend and straighten a joint. Joints that can perform both are hinge joints and ball-and-socket joints. Hinge joints move mainly in one plane, bending (flexion) and straightening (extension), like the elbow or knee. Ball-and-socket joints allow a broader range of motion, including flexion and extension as well as rotation and other directions, such as the shoulder and hip. Pivot joints mainly rotate and don’t provide true flexion/extension in the same sense, plane joints glide rather than hinge, and sutural joints are immobile. So the joints that fit the requirement are hinge joints and ball-and-socket joints.