What is the term that describes the action of decreasing the angle of a joint?

The term that describes the action of decreasing the angle of a joint is flexion. Flexion occurs when muscles contract to bring two body parts closer together, thus reducing the angle between them. For example, bending the elbow or knee involves flexion because it decreases the angle at those joints.

In contrast, extension is the opposite movement that increases the angle between body parts, such as straightening the arm or leg. Rotation describes the movement of a part of the body around its long axis, like turning the head from side to side, while abduction involves moving a limb away from the midline of the body, such as raising an arm sideways. Understanding these terms is crucial in anatomy and movement analysis, particularly in the context of physical therapy and rehabilitation.