The sacrum and the coccyx each consist of multiple bones that fuse over time. L5-S1 consists of the last bone in the lumbar spine (low back), called L5, and the triangle-shaped bone under it ...

The pelvis forms the base of the spine as well as the socket of the hip joint. The pelvic bones include the hip bones, sacrum, and coccyx. The hip bones are composed of three sets of bones that ...

A lumbosacral spine X-ray, or lumbar spine X-ray, is an imaging test that helps your doctor view the anatomy of your lower back. The lumbar spine is made up of five vertebral bones. The sacrum is ...