Rotation occurs at what type of joint?

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

Answer: (A)

Rotation around a single axis occurs at pivot joints. In this type, a bone with a rounded end fits into a ring formed by another bone and its ligaments, allowing the bone to spin around its own axis. Classic examples include the atlas rotating around the dens of the axis to turn the head from side to side, and the proximal radioulnar joints enabling forearm pronation and supination. Hinge joints are built for bending and straightening with no rotation, plane joints allow sliding movements with limited rotation, and ball-and-socket joints permit movement in multiple directions and include rotation as well, but the rotation around a single axis is most characteristic of pivot joints.