What defines flexion in terms of joint movement?

Flexion refers to the movement that decreases the angle between two body parts at a joint. When a joint undergoes flexion, it brings the articulating bones closer together, resulting in a smaller angle. For instance, when you bend your elbow to lift your hand toward your shoulder, the angle at the elbow joint decreases, illustrating the concept of flexion. This movement is commonly observed in various actions involving the limbs, such as bending the knee or lifting the arms.

The other options address different joint movements or functions. Increasing a joint angle describes extension, which is the opposite of flexion. Rotating a joint refers to the action of turning around an axis and is pertinent in movements like rotating the shoulder or hip. Stabilizing a joint involves maintaining its position, which is crucial during various activities but does not specifically describe the flexion movement. Understanding these definitions is essential for comprehending biomechanics and kinesiology in exercise physiology.