What best defines a synovial joint?

A synovial joint is best defined as a freely moveable joint characterized by the presence of a synovial cavity filled with synovial fluid, which reduces friction during movement and provides lubrication. Additionally, these joints have articular cartilage on the surfaces where the bones meet, cushioning the ends of the bones and allowing smooth movement.

The key feature that distinguishes synovial joints from other types of joints is their ability to allow a wide range of motion, which can include gliding, rotation, and angular movements. This is in contrast to fixed joints, which do not permit any movement, or slightly moveable joints, which allow limited movement, such as those found in the spine. The options mentioning only rotation or partial movement do not encompass the full range of a synovial joint’s movement capabilities, making them less accurate definitions. Thus, defining a synovial joint as a freely moveable joint with cartilage on the surface captures its essential characteristics.