Interosseous sacroiliac ligament

The interosseous sacroiliac ligament is a ligament of the sacroiliac joint that lies deep to the posterior ligament, and consists of a series of short, strong fibers connecting the tuberosities of the sacrum and ilium. It is the strongest ligament in the body. The major function of the interosseous sacroiliac ligament is to keep the sacrum and ilium together and therefore prevent abduction or distraction of the sacroiliac joint. It also helps to bear the weight of the thorax, upper limbs, head, and neck. This is performed by the nearly horizontal direction of the fibers running perpendicular from the sacrum to the ilium.