Final answer:
The articular capsule is the structure of a synovial joint that contains synovial fluid, providing lubrication and cushioning to the joint. Cartilage covers the articulating surfaces of the bones, and ligaments support the joint by holding the bones together.
Step-by-step explanation:
The structure of a synovial joint that is defined as a closed, pillow-like structure filled with synovial fluid is known as the articular capsule. This capsule forms the walls of the joint cavity that surrounds the joint, ensuring smooth movement by providing lubrication and reducing friction. The synovial fluid within the articular capsule serves as a lubricant that allows for the bones at the joint to glide over each other with minimal resistance. Moreover, the fluid provides cushioning to the ends of the bones, and the entire joint is supported by ligaments that resist dislocation and enable movement within the joint.
Cartilage, specifically hyaline cartilage called articular cartilage, covers the surfaces where bones articulate within the joint cavity, providing an additional layer of protection and smooth surface for movement. Synovial joints are the most common type of joint in the body and include varieties such as the knee and ball-and-socket joints like the shoulder, varying in the range of motion they allow.