The sacrotuberous ligament is one of the body's strongest ligaments and anchors the spine to the pelvis.

The sacrotuberous ligament is a large, fan-shaped band of connective tissue located in the posterior pelvis. It originates from the sacrum, coccyx, and ilium, then narrows to attach to the ischial tuberosity. This structure plays a critical role in the sacroiliac joint complex by limiting the upward tilting of the sacrum, a process known as nutation. Research published in the Journal of Anatomy highlights that the ligament is unique because it often shares fibers with the long head of the biceps femoris muscle. This anatomical link means that tension in the hamstrings is transmitted directly to the sacrum and the lower spine. Biomechanical studies show that this connection helps distribute forces from the lower limbs to the trunk during the gait cycle. The ligament is exceptionally strong due to its dense collagen composition and its role as a primary stabilizer of the pelvic girdle. It forms part of the boundary for both the greater and lesser sciatic foramina, which are crucial passages for nerves and blood vessels. Clinically, a tight or injured sacrotuberous ligament is a common contributor to sacroiliac joint dysfunction and sciatica. Physical therapists often target this area to relieve chronic pelvic and lumbar discomfort.