Final answer:
A synovial joint is a fluid-filled cushioning structure near a joint that helps cushion and aid tendon movements. The joint is surrounded by an articular capsule and filled with synovial fluid to reduce friction between the bones. Ligaments support the joint, while a tendon sheath surrounds a muscle tendon, allowing for smooth motions during contraction and joint movements.
Step-by-step explanation:
A synovial joint is a fluid-filled cushioning structure, lined with a synovial membrane, near a joint. It helps cushion and aid movements of tendons over bony parts. The joint is surrounded by an articular capsule that defines a joint cavity filled with synovial fluid. The articulating surfaces of the bones are covered by a thin layer of articular cartilage, which reduces friction between the bones. Ligaments support the joint by holding the bones together and resisting excess or abnormal joint motions.
A tendon sheath is a connective tissue sac that surrounds a muscle tendon at places where the tendon crosses a joint. It contains a lubricating fluid that allows for smooth motions of the tendon during muscle contraction and joint movements.