The sacrum is a large bone located between the hip bones, at the
base of the spine. The bottom part of the bone is located on top
of the coccyx, or tailbone, and the top touches the lower part
of the spine. The posterior Sacroiliac ligament is located
behind the pelvis and connects the sacrum with the ilium, which
is the upper part of the pelvis. The ligament consists of
connective tissue and the upper part moves across the ilium and
back of the sacrum bone. The lower part of the ligament connects
the back of the ilium to sacrum. The anterior ligament consists
of thin bands of connective tissue that attach to the front of
the region. The anterior Sacroiliac ligament connects the front
of the ilium to the front of the sacrum and the preauricular
sulcus. The preauricular sulcus is a grooved area on the hip
bone that exists in both men and women. The ligaments connect
the bone, creating joints in the pelvic area. Written and
medically reviewed by the Healthline Editorial Team In Depth:
Sacroiliac ligament