It connects the tuberosities of the sacrum and the ilium of the pelvis.
The interosseous sacroiliac ligament consists of a series of short, strong fibers connecting the tuberosities of the sacrum and ilium.
[citation needed] The major function of the interosseous sacroiliac ligament is to keep the sacrum and ilium together.
[2] 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.