nivelkapselin

Nivelkapselin, or the joint capsule, is the fibrous envelope that encloses a synovial joint. It consists of two main layers: the outer fibrous capsule and the inner synovial membrane. The fibrous capsule is dense connective tissue that blends with the periarticular ligaments and surrounding tissues, providing mechanical stability and restricting excessive movement. The inner synovial membrane lines the cavity of the joint on surfaces not covered by articular cartilage, and it secretes synovial fluid, which lubricates the joint and nourishes cartilage. The joint cavity contains synovial fluid, and the capsule is richly supplied with blood vessels and sensory nerves, enabling proprioception and pain perception.

Functionally, the joint capsule stabilizes the joint while permitting a range of motions dictated by the articular surfaces and ligaments. It maintains synovial fluid pressure, contributes to lubrication, and helps distribute load across the joint during movement. The capsule also houses sensory receptors that contribute to proprioceptive feedback essential for coordinated movement.

Clinical relevance includes conditions where the capsule becomes inflamed or thickened, leading to swelling, pain, and stiffness. A well-known example is adhesive capsulitis, or frozen shoulder, in which the shoulder capsule thickens and limits range of motion. Clinicians may observe characteristic capsular patterns of movement that help distinguish joint involvement from soft-tissue pathology.

Development and variation: The capsule forms from mesenchymal tissue during embryonic development and varies in thickness and reinforcement across joints, reflecting functional demands.