Which movement involves decreasing the angle of a joint?

The correct answer is flexion, as this term specifically refers to the movement that decreases the angle between two body parts at a joint. For example, when you bend your elbow or knee, you are performing flexion, as the angle formed at these joints becomes smaller.

In contrast, other movements have distinct definitions: abduction refers to moving a limb away from the midline of the body, while adduction involves bringing a limb closer to the midline. Extension, on the other hand, is the opposite of flexion; it increases the angle at a joint, such as straightening the elbow or knee after bending. Understanding these terminologies is crucial in physical therapy, as precise movement descriptions guide therapists in assessing and planning appropriate interventions for patients.