All the vertebras beyond the second and as far backward as the first sacral are united together by their bodies and processes. The bodies are connected one to another by circular discs of fibro-cartilage which intervene between them, and by the superior and inferior vertebral ligaments, the former running along the floor of the vertebral canal, to which it is attached in small festoons. The latter is situated along the under part of the bodies from the sixth dorsal vertebra to the sacrum.