Final answer:
Synovial joints have a joint cavity filled with synovial fluid, enabling wide motion range. They are stabilized by an articular capsule, articular cartilage, and ligaments, with examples including knees, elbows, and shoulders.
Step-by-step explanation:
Synovial joints are the type of joints in the human body that have a potential space between them, known as the joint cavity. This space allows for the existence of synovial fluid, which serves as a lubricant to reduce friction and enable a wide range of motion. The ends of the bones at each synovial joint are covered with articular cartilage, a type of hyaline cartilage.
This cartilage, together with synovial fluid, facilitates smooth movements at the joint. Furthermore, synovial joints are enclosed by an articular capsule made of connective tissue, which provides stability while allowing movement. Inside this capsule, the synovial fluid produced by the inner synovial membrane cushions the joint, and ligaments help to hold the bones together. Knees, elbows, and shoulders are all examples of synovial joints that allow for extensive movement like flexing and extending.