Which joints have a synovial cavity and are freely movable?

• A. Synovial joint
• B. Fibrous joint
• C. Cartilaginous joint
• D. Bony joint

Answer: (A)

Joints with a synovial cavity and freedom of movement are the synovial joints. The synovial cavity is a fluid-filled space inside a capsule that is lined by a synovial membrane, which secretes lubricating synovial fluid. This arrangement, plus articular cartilage on the ends of the bones, a fibrous joint capsule, and supporting ligaments, allows a wide range of motion seen in many joints like the knee, shoulder, and elbow. Other joint types lack this cavity: fibrous joints are joined by dense connective tissue and are usually immovable or only slightly movable; cartilaginous joints are connected by cartilage and have more limited movement; bony joints have bones fused together with no space to move. Therefore, only synovial joints meet the criteria of having a synovial cavity and being freely movable.