Which axis is associated with lateral movement?

Lateral movement refers to side-to-side motions, which are typically aligned with the sagittal plane. In a typical three-dimensional coordinate system used in biomechanics, the axis associated with lateral movement is indeed the X-axis. This axis runs horizontally, allowing for movements such as lateral flexion of the spine or side shuffling in motion.

The Y-axis usually represents vertical movement, such as up and down motions, while the Z-axis is often aligned with forward and backward movement, indicating anteroposterior motion. Therefore, when discussing lateral movements, the X-axis is the correct answer as it encompasses movements that occur side to side.