Which statement correctly describes flexion and extension at a joint?

• A. Flexion increases the angle between bones; extension decreases it; example: elbow extension when straightening to push.
• B. Flexion does not change the angle; extension increases the separation of bones.
• C. Flexion decreases the angle between bones; extension increases it; example: bending the elbow to throw.
• D. Flexion and extension are the same movement.

Answer: (C)

Flexion and extension describe how the angle between two bones at a joint changes. Flexion bends a joint, reducing that angle. Extension straightens a joint, increasing the angle toward or beyond the anatomical position. For example, bending the elbow to throw involves flexion, because the elbow angle gets smaller as the forearm moves toward the upper arm. Extending the elbow to straighten your arm, such as when pushing, increases the angle between the upper arm and forearm. So, the description that flexion decreases the angle and extension increases it, with the elbow bending as a flexion example, is the best match.