Henry Gray (18251861). Anatomy of the Human Body. 1918.
various directions. The upper part (short posterior sacroiliac ligament) is nearly horizontal in direction, and passs from the first and second transverse tubercles on the back of the sacrum to the tuberosity of the ilium. The lower part (long posterior sacroiliac ligament) is obique in direction; it is attached by one extremity to the third transverse tubercle of he back of the sacrum, and by the other to the posterior superior spine of the ilium.
The Interosseous Sacroiliac Ligament (ligamentum sacroiliacum interosseum).This ligament lies deep to the poserior ligament, and consists of a series of short, strong fibers connecting the tubeosities of the sacrum and ilium.