The bony spinal column runs from the base of the skull to the tip of the tailbone. The spinal column is made up of stacked vertebral bones: 7 neck (cervical) vertebral bones, 12 chest (thoracic) vertebral bones, 5 lower-back (lumbar) vertebral bones, the sacrum, and the tailbone (coccyx).
The vertebral bones of the neck, chest, and lower back all share a similar basic design. The cylinder-shaped body (asterisk), the largest part of the vertebral bone, is designed for weight-bearing. Little Mickey Mouse ear-shaped structures sticking up and down from each vertebral bone lock each vertebral bone to its neighbors from above and below. Tiny joints, called facet joints (arrows) are formed where the vertebral bones interlock with their neighbors, stabilizing the spine.