Expansion
The head articulates with two vertebral bodies; the tubercle articulates with one transverse process
Expansion
- Costovertebral joint - between the head of the rib and the demifacets of its own vertebra and the one above, spanning the intervertebral disc
- Costotransverse joint - between the tubercle of the rib and the transverse process of its own vertebra
Both are synovial plane joints, and together they define the axis about which the rib rotates. That axis is what produces pump handle movement above and bucket handle movement below.
The exceptions are worth learning as a group: ribs 1, 10, 11 and 12 have a single facet on the head, and ribs 11 and 12 lack a tubercle and therefore have no costotransverse joint, which is also why they are called floating ribs.