Corpus: Iliolumbar ligament

The iliolumbar ligament is a ligament that runs from the costal processes of the fourth and fifth lumbar vertebrae to the iliac crest and the anterior sacroiliac ligaments. Its upper parts merge into the thoracolumbar fascia.

The fibres that originate at the fourth lumbar vertebra run posteriorly and vertically, the fibres from the fifth lumbar vertebra run anteriorly and horizontally. Due to the connections between the fibres and the iliac crest, the movements of both lumbar vertebrae are coupled with the iliac bone and vice versa. The quadratus lumborum muscle runs between the two parts of the ligament. The iliopsoas muscle lies on the ventral side and the erector spinae muscle on the dorsal side.

The iliolumbar ligament improves pressure transmission in the joint space of the sacroiliac joint and thus prevents the pelvic blades from moving apart under heavy loads. Poul-Goudzwaard et al. (2003) were able to demonstrate that the amplitude of movement of the sacroiliac joint increases significantly after cutting both parts of the ligament.