Which region of the spine has the least range of motion?

The lumbar region of the spine is primarily designed for stability and load-bearing, which limits its range of motion compared to other spinal regions. It consists of five vertebrae in the lower back and is responsible for supporting the upper body's weight while allowing some degree of movement like flexion and extension. However, unlike the cervical region, which permits a wide range of motion including rotation and lateral flexion, and the thoracic region, which allows for rotational movement in conjunction with rib articulation, the lumbar region's structure and alignment focus more on stability and less on extensive mobility.

The sacral region, although fused and thus immobile, is not typically associated with a "range of motion" in the same way as the others because it acts as a supportive base. Therefore, the lumbar region distinctly has the least range of motion in functional activities when compared to the dynamic capabilities of the cervical and thoracic regions. This emphasis on stability rather than mobility is a key characteristic of the lumbar spine's function.