Which type of spine movement involves bending forward or backward?

The movement of bending forward or backward in the spine is known as flexion and extension. Flexion specifically refers to the action of bending forward, which decreases the angle between the body parts, such as when bringing the torso toward the thighs. On the other hand, extension refers to the movement of bending backward, which increases the angle between those same body parts, such as when lifting the torso away from the thighs. Both movements are essential in understanding how the spine functions during various physical activities and are foundational concepts in anatomy and movement practices.

In this context, while other types of movements like rotation or lateral flexion involve different actions—turning around an axis or bending to the side—flexion distinctly encompasses both the forward and backward bending motions, thereby making it the right choice for the question.