Each of these joints is formed by the articulation of the head of a rib between the bodies of two vertebrae, and by the union of the tubercle of the rib with the transverse process of the vertebra behind it. Several small ligaments enter into each joint and unite the rib firmly to the spine, while at the same time permitting free play of one bone upon the others.

Fig. 349. - Articulation of the Ribs and Spine.

1. Common inferior vertebral ligament. 2, 2, 2. Inferior costo-vertebral ligaments. 3. Inter-articular costo-vertebral ligament. 4. Inter-vertebral fibro-cartilage in section.