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 ...

Abduction – movement away from the midline of the body. This occurs at the hip and shoulder joints during a jumping jack movement. Adduction – movement towards the midline of the body.

Each role is vital to proper arm function and can only occur when the anatomy around the shoulder is uncompromised. The presence of bony and soft tissue injury as well as muscle weakness and ...