The sacrum and the coccyx each consist of multiple bones that ... increase the vulnerability of the L5-S1 junction even more.

Likewise, hip pain that radiates down the legs can also originate in the sacroiliac (SI) joint, rather than the hip joint.

Your SI joint, or sacroiliac joint, connects your sacrum (otherwise known as the tailbone) and your illiac, the bone of the topside of your pelvis. Technically, there's two of these joints—one on ...

There are 5 sacral vertebrae, which are fused as one bone and known as the sacrum, in the sacral region. There are 3 to 5 coccygeal vertebrae, which are fused as one bone and known as the coccyx ...