Where does the most sagittal motion occur in the lumbar spine?

The lumbar spine is designed to facilitate a range of motions, with sagittal motion, which includes flexion and extension, being particularly significant. The most pronounced sagittal motion occurs primarily at the lower lumbar vertebrae due to the structure of the intervertebral discs and the orientation of the facet joints.

L1 and L2 are situated higher in the lumbar spine, where there is still some degree of flexion and extension allowed, but it is the lower lumbar regions, particularly L3 and L4, where the architecture of the vertebrae and the corresponding facet joint orientation enable greater movement. As one examines the lumbar vertebrae from L1 to L5, the degree of sagittal motion generally increases toward L4 and L5, which are designed to handle increased loads and mobility.

This implies that the choice indicating L1 and L2 as the location of most sagittal motion is not aligned with the biomechanics of the lumbar region, as L4 and L5 exhibit the most motion relative to the surrounding structures. The anatomical traits of L3, L4, and L5, including the larger size and thicker intervertebral discs at these levels, facilitate this increased flexibility in sagittal plane movements.