The joint capsule is a fibrous structure that surrounds and encloses a joint, providing stability and support. It is composed of two layers: an outer fibrous layer that connects to the bones and an inner synovial membrane that produces synovial fluid. This fluid lubricates the joint, reducing friction during movement. The joint capsule plays a crucial role in maintaining joint health and function. It helps protect the joint from injury and allows for a range of motion while preventing excessive movement that could lead to damage. Proper functioning of the joint capsule is essential for activities involving the musculoskeletal system.