What does the term extension primarily involve?

The term extension primarily involves increasing the angle between body parts. In anatomical terms, extension occurs when two segments of the body move away from each other, resulting in a larger angle at the joint. For example, when you straighten your arm at the elbow, you are extending the elbow joint, which increases the angle between the forearm and the upper arm. This movement is essential in various physical activities, where increasing the angle allows for a wider range of motion and functionality.

In contrast, the other options relate to different types of movements or actions in the body. Decreasing the angle between body parts refers to flexion, which is the opposite of extension. Rotating a limb describes a different motion called rotation, while bending a limb is typically associated with flexion as well. Understanding these distinctions is crucial for accurately describing movements and positions in the anatomical context.