Final answer:
Semi-elastic structures surrounding major joints include articular capsules, supported by muscles and tendons. The articular discs and menisci serve functions of shock absorption and smooth bone articulation within synovial joints.
Step-by-step explanation:
The semi-elastic structures that surround major joints are known as articular capsules. These are made of connective tissue and allow movement of the joint while also resisting dislocation. Within many synovial joints, additional support is provided by muscles and tendons, which act as a dynamic system to maintain joint stability. A tendon is a dense connective tissue structure that attaches a muscle to bone, helping to support the joint by adjusting muscle contractions in response to increased forces acting on the joint.
Additional structures like articular discs or menisci can serve various functions, such as shock absorption, cushioning, and promoting smooth movements between the articulating bones. These can be found in joints such as the sternoclavicular joint, between the radius and ulna, or in the knee. Synovial fluid within the joint cavity, the presence of articular cartilage, and the involvement of ligaments also contribute to the characteristic features and indirect support of synovial joints.