The vertebrae are irregularly shaped bones which stack together to form the spinal column. The |vertebrae| are connected together by ~ligaments~ and muscles which control the degree of flexibility of the |spine|. The |vertebrae| are cushioned from each other by ~cartilage~ disks which act as |shock| absorbers to protect the |vertebrae| in the |spine|. The |vertebrae| may be separate (cervical, thoracic, and |lumbar vertebrae|), semi-articulated (as in some |coccygeal| |vertebrae|), or fused (as in the |sacrum| and |coccyx|). The typical vertebra has a body of solid bony material, which supports the weight of the |spine|, and an arch, which forms the vertebral ~foramen~. It is the adjoining vertebral foramina which creates a canal down through the spinal column which houses and protects the |spinal cord|. The |thoracic vertebrae| feature ~facets~ to which the |ribs| attach, called ~costal~ ~facets~ (because of their relation to the |ribs|).
