Which type of joint is found at the hip and shoulder, allowing a wide range of motion?

• A. Pivot joint
• B. Ball and socket joint
• C. Hinge joint
• D. Saddle joint

Answer: (B)

Movements in joints are determined by how the bones articulate. The hip and shoulder are ball-and-socket joints, where a spherical head fits into a rounded socket. This shape lets the limb move in many directions: forward and backward (flexion and extension), away from and toward the midline (abduction and adduction), rotation around the limb’s long axis, and even circular motion (circumduction). The trade-off is stability, as the socket is not as deeply constraining as in some other joints, but the overall range of motion is unparalleled, which is why these joints are described as having a wide range of motion. Other joint types restrict movement to single planes or axes—for example, hinge joints mainly bend and straighten in one plane, pivot joints rotate around a single axis, and saddle joints allow complex motion but not the full rotation of a ball-and-socket joint.