Corpus: Sacrospinous ligament

The sacrospinous ligament is a flat, triangular ligament at the back of the pelvis, between the sacrum and the ischium.

The sacrospinous ligament has a broad-based insertion at the lateral edge of the sacrum and the coccygeal bone. From here it runs to the tip of the ischial spine (spina ischiadica).

Just behind the sacrospinous ligament is another important ligament of the posterior pelvic region, the sacrotuberous ligament, with which it exchanges some fibres. Together, these ligaments form the lesser sciatic notch at the lesser sciatic foramen, which creates a connection between the lesser pelvis and the tigh. The upper edge of the sacrospinous ligament is also involved in the formation of the greater sciatic foramen.

Anteriorly, the ligament is closely connected to the coccygeus muscle and serves as the origin of parts of the muscle.

The sacrospinous ligament serves to secure the sacroiliac joint. Its main task, together with the sacrotuberous ligament, is to prevent dorsal tilting of the sacral bone in the transverse axis. As the two ligaments are long dorsal lever arms, they are particularly effective.