Sacral region (bottom of the spine) – located below the lumbar spine, the sacrum is a series of 5 bony segments fused together (known as S1 to S5) that create a triangular-shaped bone that serves as the base of the spine and makes up part of the pelvis.

What are the parts of the spine?

The spine itself has three main segments: the cervical spine, the thoracic spine, and the lumbar spine. The cervical is the upper part of the spine, made up of seven vertebrae (bones). The thoracic is the center portion of the spine, consisting of 12 vertebrae. The lower portion of the spine is called the lumbar spine.

What connects the pelvis to the spine?

The sacroiliac joints link your pelvis and lower spine. They’re made up of the sacrum — the bony structure above your tailbone and below your lower vertebrae — and the top part (ilium) of your pelvis. There are sacroiliac joints in both the right and left sides of your lower back.