The sacrotuberous ligament is a slender, fan-shaped ligament of the posterior (back) pelvis located on either side of the body. This ligament arises midway down the posterior side of the sacrum, which is located at the spinal base.

It is largely comprised of collagen fibers and is strong enough to support the sacrum and prevent it against moving from its position under the body weight.

The connective tissue in this ligament joins with various other tissues, particularly the biceps femoris muscular tendon, which is associated with an important muscle of the hamstrings on the posterior thigh region. It is also a ligament of the sacroiliac joint, which is connected to the sacrum.

This ligament can become stressed during aggressive physical activities and sports that may cause the arching of the spine. If it becomes strained or injured, it may result in problems similar to those of a typical iliolumbar ligament injury. The ossified, or bony, sacrotuberous ligament may be a critical factor in different types of neurovascular compression syndromes (the abnormal compression of nerves and blood vessels). An anatomical understanding of this ligament is crucial in order for patients to receive proper treatment for this clinical condition.