Photograph of the human third lumbar vertebra (L3), one of five bones that comprise the lumbar spine of the lower back. The vertebra is seen in superior aspect with the dorsal surface at top: in other words, one is looking at the anatomical upper surface of the bone with its back-facing side at top. Lumbar vertebrae have large, wide bodies - the disc-like bone at bottom; the bony processes (spinous at top, transverse at left and right) are relatively short and thickened and are used as anchorages for the strong muscles of the lower back. The central opening (the vertebral canal) accommodates the spinal cord.