Corpus: Sacrotuberous ligament
1. Definition
2. Anatomy
The sacrotuberous ligament has a broad-based insertion on the posterior superior iliac spine, on the lateral edge and on the transverse tuberosities IV and V of the sacral bone and on the upper part of the coccygeal bone. From here it runs caudally, ventrally and laterally to the inner edge of the ischial tuberosity (tuber ischiadicum), where it is somewhat fanned out. From there, some fibres continue as a sickle-shaped extension along the ischial tuberosity.
Just in front of the sacrotuberous ligament is another important ligament of the posterior pelvic region, the sacrospinous 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 thigh. The upper edge of the sacrotuberous ligament is also involved in the formation of the greater sciatic foramen.
Inferiorly, the ligament forms a unit with the tendon of origin of the caput longum of the biceps femoris muscle. It also serves as an area of origin for the gluteus maximus muscle and the fascia lata.
3. Function
The sacrotuberous ligament serves to secure the sacroiliac joint. Together with the sacrospinous ligament, its main function is to prevent dorsal tilting of the sacral bone in the transverse axis. As both ligaments are long dorsal lever arms, they are particularly effective.