Which joint category includes hinge, saddle, and ball-and-socket joints?

• A. Non-synovial joint
• B. Fibrous joint
• C. Synovial joint
• D. Cartilaginous joint

Answer: (C)

Hinge, saddle, and ball-and-socket joints are all synovial joints. This category is defined by a fluid-filled joint cavity that allows a wide range of motion, plus an articular capsule, synovial membrane with synovial fluid, articular cartilage on the joint surfaces, and reinforcing ligaments. The diverse movements of these joints—from the bending of a hinge, to the multi-directional movement of a saddle joint, to the ball-and-socket’s multiaxial rotation—demonstrate the flexibility that a synovial joint provides. In contrast, non-synovial joints (fibrous or cartilaginous) lack a joint cavity and are generally immovable or only slightly movable.