Prenatal development of the iliolumbar ligament

Serial sections, in the frontal plane, of 12 human fetuses showed that the iliolumbar ligament was always present at the gestational age of 11 to 15 weeks; in younger specimens, it could not be identified. The ligament develops during the prenatal period and is not formed by metaplasia of the quadratus lumborum muscle during the second decade of life.