Sacroiliac (SI) Joints (arthrodial) – the junction between the “auricular” surfaces of the sacrum and the “auricular” surfaces of the ilium. The function of the sacroiliac joint is to transmit weight from the upper body through the vertebral column to the hips and femurs. The sacroiliac ligaments support the SI joint on the anterior and posterior surfaces of the joint. - Short Posterior Sacroiliac Ligament: attaches from the
posterior surface of the upper sacrum to the posterior surface of the ilium.
- Long Posterior Sacroiliac Ligament: runs vertically
from the posterior superior iliac spine to the lower sacrum.
- Anterior Sacroiliac Ligament: attaches from the anterior
surface of the sacrum and ala to the auricular surface of ilium, stabilizing the anterior surface of the joint.
- Sacrotuberous Ligament: a triangular ligament that
attaches from the sacrum to the ischial tuberosity.
- Sacrospinous Ligament: a triangular ligament that
attaches from the sacrum to the ischial spine.
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