Iliolumbar ligament Anatomy Figure 1. The Sacroiliac Ligaments from Grays Anatomy The location of the iliolumbar ligaments is between the iliac crest to transverse process of L4 and L5. The nerves from the L4 and L5 ventral rami pass around the Iliolumbar ligaments as shown in figure 2. Kim (2017) examined 14 fixed cadavers and found huge variation in the routes of the L4 and L5 lumbosacral trunks relative to the inferior and superior bands of the iliolumbar ligaments. With both passing anteriorly or posteriorly variously in multiple combinations amongst different cadavers. IB=...