In addition to these ligaments the joint is strengthened by the iliolumbar and lateral lumbosacral ligaments.
The most commonly disrupted and/or torn ligaments are the iliolumbar ligament and the posterior sacroiliac ligament.
The lateral lumbosacral ligament is partly continuous with the iliolumbar ligament.
The iliolumbar ligament passes between the tip of the transverse process of the fifth lumbar vertebra and the posterior part of the iliac crest.
Other less prominent sources of blood supply include radicular arterial branches from the aorta, lateral sacral arteries, and the fifth lumbar, iliolumbar, and middle sacral arteries.
Generally, the artery divides into an anterior division and a posterior division, with the posterior division giving rise to the superior gluteal, iliolumbar, and lateral sacral arteries.
The lateral lumbosacral ligament, partly continuous with the iliolumbar ligament, passes down from the lower border of the transverse process of the fifth vertebra to the ala of the sacrum.
