Explores the anatomy and functions of human joints, categorizing them ... the ball-and-socket joint of the shoulder and hip, and the complex structure of the knee. The film describes the movements ...

Four important synovial joints used in most sporting actions are the elbow and shoulder joints in the arm, and the knee and hip joints in the leg. The elbow and knee joints are both hinge joints.

Ball and socket joints also allow flexion and extension. Flexion of the shoulder joint occurs when the humerus (upper arm) moves forwards from the rest of the body, which happens at the end of an ...