A joint that contains a cavity is typical of which joint type?

• A. Synovial
• B. Hinge
• C. Pivot
• D. Fibrous

Answer: (A)

Having a space filled with fluid between the bones is the hallmark of synovial joints. This cavity, the synovial cavity, houses synovial fluid that lubricates the joint and allows smooth, wide-ranging movement. The joint is enclosed by a capsule and lined with a synovial membrane, and the surfaces are covered with articular cartilage. That cavity-containing setup is what makes these joints freely movable, or diarthroses.

Fibrous joints don’t have a joint cavity; they’re held together by dense connective tissue and are usually immovable or only slightly movable. Hinge and pivot describe specific forms within the synovial group, so they also have cavities, but the defining category for a cavity-bearing joint is the synovial type.