Articular cartilage serves to:

A. Ligaments:Ligaments stabilize and limit joint movement but do not primarily reduce friction.
B. Articular cartilage: Articular cartilage provides a smooth, low-friction surface and shock absorption, helping reduce friction.
C. Joint capsule: The joint capsule encloses and stabilizes the joint and contains synovial fluid but is not the main friction-reducing element.
D. Synovial fluid: Synovial fluid lubricates the joint surfaces, nourishes cartilage, and significantly reduces friction during movement.

A. Saddle:Saddle joints allow biaxial movement (for example the thumb carpometacarpal joint) but do not provide the greatest overall range of motion.
B. Hinge:Hinge joints permit movement primarily in one plane (flexion and extension), limiting their range compared with multiaxial joints.
C. Pivot:Pivot joints allow rotation around a single axis (for example the atlantoaxial joint) and therefore have a restricted range of motion.
D. Ball-and-socket:Ball-and-socket joints permit multiaxial movement including flexion/extension, abduction/adduction, and rotation, offering the greatest range of motion.