There is (mainly, in terms of movement) a ball-and-socket joint in the shoulder; a hinge joint in the elbow; and various joints inside the wrist which work together at different bones.
fixed joint
the solar system of your mama
The knee helps your leg flex and extend.
The hamstrings flex the knee and extend the hip.
One set to flex a joint, the other to extend a joint.
A chicken's wing has muscles that control the movement of the elbow joint. These muscles contract and relax to move the wing up and down, allowing for flight and other wing-related activities. The tendons in the wing help transmit the force generated by the muscles to the bones, enabling movement at the elbow joint.
The Biceps flex the elbow The Triceps extend the elbow
Quadriceps contracts to extend the knee joint. Rectus femoris, the part of quadriceps flex the hip joint on the thigh.
The quadriceps femoris group extends the leg at the knee joint. It is responsible for straightening the knee and kicking movements.
Biceps flex the arm at the elbow, and triceps (along with the brachialis) extend it. The deltoids raise the arms.
The triceps muscles extend (straighten) the arm, while the biceps muscles flex (bend) it at the elbow joint.
The muscles responsible for flexing and extending your lower leg are the quadriceps and hamstrings, while the muscles responsible for flexing and extending your upper arms are the biceps and triceps, respectively. These muscle groups work in opposition to each other to facilitate these movements.