Ligament · Lumbar spine

Iliolumbar ligament

Ligamentum iliolumbale

A strong band anchoring the lowest lumbar vertebra to the pelvis. It runs from the tip and lower edge of the fifth lumbar transverse process — often with a second slip from the fourth — outward to the inner lip of the iliac crest, with deeper fibres continuing to the front of the sacroiliac joint. It is the only ligament tying the mobile lumbar spine directly to the pelvic ring, and it is what resists the last vertebra sliding forward down the sloping top of the sacrum. In children it is partly muscular, becoming fully fibrous in adult life.