The sacrotuberous ligament is one of the two primary pelvic floor ligaments resisting sacral nutation, connecting the posterior sacrum to the ischial tuberosity. It forms the posterior boundary of the lesser sciatic foramen (through which the pudendal nerve and internal pudendal vessels pass on their way to Alcock's canal). The long head of biceps femoris attaches to its distal end, creating a myofascial tension-sharing system.
| Origin | Posterior iliac spine, posterior sacrum, and coccyx |
|---|---|
| Insertion | Ischial tuberosity (inner border and medial aspect) |
| Actions | Resists sacral nutation; forms the lesser sciatic foramen with the sacrospinous ligament; anchors the biceps femoris long head and gluteus maximus |
|---|
Sacrotuberous ligament tenderness on direct palpation is assessed in sacroiliac joint evaluation. The pudendal nerve passing through the lesser sciatic foramen can be compressed between the sacrotuberous and sacrospinous ligaments producing pudendal neuralgia — managed with ultrasound-guided nerve block at the ischial spine or surgical decompression.
Pudendal nerve entrapment between the sacrotuberous and sacrospinous ligaments producing perineal pain managed with nerve block and surgical decompression.
