Final answer:
The facet joints are synovial plane joints between vertebrae that provide limited motion, with stretched capsules aiding in restraining forward movement of superior vertebrae. Different regions of the spine have varying degrees of allowable motions, and reduced facet contact areas can lead to damage. Protective ligaments such as the anterior longitudinal ligament prevent excess backward bending.
Step-by-step explanation:
The facet joints, also known as zygapophysial joints, are synovial joints that connect the articular processes of adjacent vertebrae. These joints allow for limited movements such as flexion, extension, lateral flexion, and rotation, which vary depending on the region of the vertebral column. The stretched capsule of facet joints helps restrain the forward migration of the superior vertebrae. However, with reduced contact area on the facets, the potential for damage over time increases due to the greater concentration of stress on smaller areas of the joint surfaces during movements. In the cervical region, the orientation of the articular processes provides extensive ranges of motion. In comparison, the thoracic region's range of motion is limited due to the structure of the vertebrae and the rib cage attachment. The lumbar region allows for considerable extension and flexion but limits rotation. Protective structures of the vertebral column, such as the anterior longitudinal ligament, prevent excessive backwards bending and potential injuries like whiplash.