What is a diarthrosis?

• A. A slightly movable joint with limited motion.
• B. A freely movable joint, typically synovial.
• C. A joint with no movement.
• D. A joint bound by fibrocartilage only.

Answer: (B)

A diarthrosis refers to a joint that is freely movable, usually a synovial joint. These joints have a joint cavity filled with synovial fluid, wrapped in an articular capsule with a synovial membrane, and articular cartilage covering the moving bones. This setup minimizes friction and allows a wide range of motion in multiple directions, as seen in the knee, elbow, shoulder, and hip. So describing a joint as freely movable and typically synovial directly matches what a diarthrosis is.

The other options describe different mobility levels or joint types: an amphiarthrosis is only slightly movable, a synarthrosis has no movement, and a joint bound by fibrocartilage points to cartilaginous joints that aren’t freely movable.