What type of movement does "flexion" typically refer to in joint action?

Flexion refers to the action of decreasing the angle between two body parts, typically at a joint. For example, when you bend your elbow or knee, you are decreasing the angle between the forearm and upper arm or thigh and lower leg, respectively. This action brings the sections of the limb closer together.

In contrast, the other options describe different types of movements. Increasing the angle between two body parts is called extension, while rotating a bone around its axis involves a different motion known as rotation. Therefore, the correct understanding of flexion is essential for recognizing how joints function in relation to muscle movement and overall body mechanics.