Which statement about the movement contribution of L5-S1 is true?

Which statement about the movement contribution of L5-S1 is true?

• A. It accounts for the least lumbar movement
• B. It accounts for the most lumbar movement
• C. It does not contribute to lumbar movement
• D. It accounts for equal movement as L4-L5

Answer: (B)

The movement at the last lumbar segment, where L5 meets the sacrum, is the main driver of lumbar range of motion. This joint forms the pivotal link between the mobile lumbar spine and the relatively fixed sacrum, and its articular surfaces and disc are oriented to favor flexion and extension. Because the sacrum is anchored to the pelvis, most of the lumbar motion is produced at this junction, making L5-S1 contribute more to overall lumbar movement than the other lumbar segments. So the statement that this level accounts for the most lumbar movement aligns with how the lumbosacral junction behaves during bending and lifting, while options claiming minimal, no, or equal movement to the next segment don’t fit with this primary hinge role.

The movement at the last lumbar segment, where L5 meets the sacrum, is the main driver of lumbar range of motion. This joint forms the pivotal link between the mobile lumbar spine and the relatively fixed sacrum, and its articular surfaces and disc are oriented to favor flexion and extension. Because the sacrum is anchored to the pelvis, most of the lumbar motion is produced at this junction, making L5-S1 contribute more to overall lumbar movement than the other lumbar segments. So the statement that this level accounts for the most lumbar movement aligns with how the lumbosacral junction behaves during bending and lifting, while options claiming minimal, no, or equal movement to the next segment don’t fit with this primary hinge role.