Pain in the Long Dorsal Sacroiliac Ligament
The long dorsal sacroiliac ligament lies between the PSIS (posterior superior iliac spine) and sacrum (lateral S3, S4) and the ischial tuberosity.
It has strong anatomical connections with the erector spinae, the thoracolumbar fascia, the gluteus maximus, the sacrotuberous ligament and the SI-capsule.
Pain can be found just below the PSIS.
Functionally the ligament works opposite to the sacrotuberous ligament.
Anterior rotation of the sacrum decreases the tension on the long dorsal sacroiliac ligament. This contrasts with the tension that increases within the sacrotuberous ligament because of this anterior sacral rotation.
Posterior rotation of the sacrum leads to the opposite; more ‘tension’ (stretch) in the long dorsal sacroiliac ligament.
Traction on the biceps femoris muscle barely produces any tension in the long dorsal sacroiliac ligament but creates strong amounts of ‘tension’ in the sacrotuberous ligament.