It is because we have joints and muscles
Joints and muscles
Muscles that cross two joints and act on both joints are called biarticular muscles. These muscles can generate movement at both joints they cross, which can have implications for muscle function and coordination during activities involving those joints.
Polymyalgia rheumatica
it keeps the muscles strong becuase they and allways being used if you exercise and the joints and flexible because they and always being moved about
No, smooth muscles are not responsible for movements across movable joints. Smooth muscles are found in the walls of hollow organs such as the blood vessels and the digestive tract. Skeletal muscles, which are attached to bones across movable joints, are responsible for producing movements by pulling on bones.
All the synovial joints that are used in normal daily activities, like the muscles and joints of the arms and legs.
JOINTS
The hamstrings and gluteous maximus are main muscles involved in diving and the pivot joints on your knee are the main joints you use.
Cartilaginous joints such as those in your spine allow very limited movement.
joints
tendon