they are specifically rotations and tilts of the sacrum on the ilium and on L5, the 5th lumbar vertebra. Sacroiliac disorders include movements around diagonal axes, unilateral sacral flexion ...

The lumbar region is located between the thoracic (chest) region of the spine and the sacrum, a large bone at the base of the spine. The lumbar spine usually curves slightly inward, called lordosis.

the L5-S1 disc is a spinal joint found at the bottom of the lumbar spine (L5) and top of the sacrum (S1). This disc is ...