Pelvic ligaments

Question 1

Sacroiliac ligaments

Answer 1

Anterior sacroiliac ligament
- Multiple thin strands forming a strong flat band anterior to the SIJs
- Extends from pelvic surface of sacrum to ilium

Posterior sacroiliac ligaments
- Two posterior sacroiliac ligaments
- Short (deep)
- Horizontal fibres from the sacrum to the iliac tuberosity
- limits forward movt of the sacrum
- Long (superficial)
- More vertical fibres PSIS to transverse tubercles of the sacrum
- limits downward movt of the sacrum with respect to the ilium

Interosseous sacroiliac ligament
- Deepest posterior ligaments
- Short, thick + strong
- Directly posterosuperior to the articular (auricular) surface at S1 + S2 level
- Restricts separation of the SIJ

Question 2

Accessory ligaments

Answer 2

Accessory ligaments:
Sacrotuberous ligament (extra-capsular)
- nearly vertical ligament attaching b/w the sacrum + ischial tuberosity

Sacrospinous ligament (extra-capsular)
- nearly horizontal ligament attaching b/w the ischial spine + sacrum

Iliolumbar ligaments (extra-capsular)
- L5 to ilia bilaterally
- multiple strands
- stabilises the lumbosacral joint