What term describes the action when the joint angle decreases?

The term that describes the action when the joint angle decreases is flexion. Flexion occurs when two body parts move closer together, effectively reducing the angle between them at a joint. This movement is commonly observed in various joints throughout the body, such as when the elbow bends or when the knee is brought closer to the body.

Flexion can be understood in contrast to other movements defined within joint action vocabulary, such as extension, which increases the angle between body parts, or rotation, which involves turning around an axis. Abduction refers to the movement away from the midline of the body, which is fundamentally different from the action of decreasing a joint's angle. This distinction is crucial in anatomical studies and can aid in understanding the range of motion and functional movements in both veterinary and human anatomy.