FIGURE 2.

Variation at the sacrococcygeal border based on CT generated 3D models of the human sacrum (depicted in gray) (a, b) ligaments of the sacrococcygeal joint, including the ligamentum sacrococcygeum laterale (dark blue), the lig. interarticulare (light blue), the lig. posterius superficiale (yellow) and the lig. posterius profundum (orange) in dorsal (a) and lateral (b) view. (c–j) Four exemplary specimens of the sacrococcygeal border in dorsal (c, e, g, i) and lateral (d, f, h, j) view. In (c–f), the cornua between the sacrum and the coccyx are not fused. In (g–j), the lateral and interarticular ligaments have calcified, leading to the sacralization of the first coccygeal vertebra