The sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments (with which it is partly blended), to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx.

Its oblique fibres descend laterally, converging to form a thick, narrow band that widens again below and is attached to the medial margin of the ischial tuberosity.

When present it extends towards the ischioanal fossa travelling along the ischial ramus and fusing with the obturator fascia.

The lower border of the ligament was found to be directly continuous with the tendon of origin of the long head of the biceps femoris in approximately 50% of subjects.

This article incorporates text in the public domain from page 309 of the 20th edition of Gray's Anatomy (1918)