Which motion is least enabled in the thoracic spine due to facet orientation?

Which motion is least enabled in the thoracic spine due to facet orientation?

• A. Rotation
• B. Flexion
• C. Circumduction
• D. Lateral flexion

Answer: (C)

Thoracic facet joints are oriented mainly in a plane that favors movements in certain directions and resists others. This arrangement limits complex, multi-directional motion at a single spinal segment. Circumduction—a circular, multi-plane motion around a joint—is not a true single–joint movement for a vertebral motion segment; it would require coordinated movement through flexion, extension, abduction, adduction, and rotation in a circular path, which the thoracic facet orientation cannot provide at one level. In contrast, the spine can perform distinct components such as flexion/extension, lateral flexion, and rotation (though each is limited by the rib cage and facet alignment). Hence circumduction is the least enabled motion in the thoracic spine due to how the facets are set up.

Thoracic facet joints are oriented mainly in a plane that favors movements in certain directions and resists others. This arrangement limits complex, multi-directional motion at a single spinal segment. Circumduction—a circular, multi-plane motion around a joint—is not a true single–joint movement for a vertebral motion segment; it would require coordinated movement through flexion, extension, abduction, adduction, and rotation in a circular path, which the thoracic facet orientation cannot provide at one level. In contrast, the spine can perform distinct components such as flexion/extension, lateral flexion, and rotation (though each is limited by the rib cage and facet alignment). Hence circumduction is the least enabled motion in the thoracic spine due to how the facets are set up.