What is the most mobile area in the lumbar spine?

What is the most mobile area in the lumbar spine?

• A. L5-S1
• B. Lumbosacral junction
• C. L1-L2
• D. L4-L5

Answer: (B)

The area where the lumbar spine meets the sacrum has the greatest range of motion. This lumbosacral junction, the last lumbar vertebra and the first sacral segment, acts as the hinge that allows the most bending of the lower back, especially flexion and extension, with some additional side bending. Because the sacrum is fused to the pelvis, most movement is concentrated at this junction, making it the most mobile part of the lumbar region. The levels above are more restrained by facet joints and ligaments, so they don’t move as much as the lumbosacral junction.

The area where the lumbar spine meets the sacrum has the greatest range of motion. This lumbosacral junction, the last lumbar vertebra and the first sacral segment, acts as the hinge that allows the most bending of the lower back, especially flexion and extension, with some additional side bending. Because the sacrum is fused to the pelvis, most movement is concentrated at this junction, making it the most mobile part of the lumbar region. The levels above are more restrained by facet joints and ligaments, so they don’t move as much as the lumbosacral junction.