Which statement is NOT true regarding the iliolumbar ligament?

Which statement is NOT true regarding the iliolumbar ligament?

• A. It is a possible remnant of the transversospinalis muscles
• B. It reinforces the iliac region
• C. It prevents anterior shear of L5 on S1
• D. It attaches to the iliac crest and transverse processes

Answer: (A)

The iliolumbar ligament is a key stabilizer of the lumbosacral junction. It forms a strong band from the transverse processes of L4–L5 and extends to the iliac crest, sometimes with anterior and posterior fibers blending with surrounding fascia and muscles. By anchoring the lower lumbar spine to the ilium, it helps prevent forward (anterior) slipping of L5 on S1 and adds reinforcement to the pelvic-hip region where the spine meets the pelvis. This stabilizing role is why its attachment to the iliac crest and lumbar transverse processes is important and why it’s described as reinforcing the lumbopelvic area. The idea that it is a remnant of the transversospinalis muscles isn’t correct. The iliolumbar ligament is a distinct fibrous structure, not a vestigial muscle or a remnant of the deep back muscles like the transversospinalis group (which includes the multifidus and semispinalis). While these muscles contribute to spinal stability in other ways, the iliolumbar ligament itself is a separate ligamentous connection between the iliac crest and lumbar transverse processes.

The iliolumbar ligament is a key stabilizer of the lumbosacral junction. It forms a strong band from the transverse processes of L4–L5 and extends to the iliac crest, sometimes with anterior and posterior fibers blending with surrounding fascia and muscles. By anchoring the lower lumbar spine to the ilium, it helps prevent forward (anterior) slipping of L5 on S1 and adds reinforcement to the pelvic-hip region where the spine meets the pelvis. This stabilizing role is why its attachment to the iliac crest and lumbar transverse processes is important and why it’s described as reinforcing the lumbopelvic area.

The idea that it is a remnant of the transversospinalis muscles isn’t correct. The iliolumbar ligament is a distinct fibrous structure, not a vestigial muscle or a remnant of the deep back muscles like the transversospinalis group (which includes the multifidus and semispinalis). While these muscles contribute to spinal stability in other ways, the iliolumbar ligament itself is a separate ligamentous connection between the iliac crest and lumbar transverse processes.