What is the term used to describe the action of increasing the angle of a joint?

The action of increasing the angle of a joint is known as extension. This term specifically refers to movements that straighten or elongate the joint, moving the segments of the body further apart, which results in a larger angle between them. For example, when you straighten your arm at the elbow or lift your leg backwards at the hip, you are performing an extension.

In contrast, flexion refers to decreasing the angle of a joint, bringing the two body parts closer together. Abduction involves moving a limb away from the midline of the body, while adduction brings it closer to the midline. Understanding these terms is key to accurately describing physical movements and analyzing human motion or anatomy.