Which area is listed as not allowing coupled motion?

• A. C1
• B. C2
• C. Thoracic spine
• D. Occiput

Answer: (D)

Coupled motion is the idea that movement in one plane often brings about movement in another due to joint anatomy. In the skull-base region, the atlanto-occipital joint between the occiput and the first cervical vertebra is built mainly for nodding—flexion and extension—with little accompanying rotation or lateral bending. Because of this design, there isn’t a consistent pattern where rotation is coupled with lateral flexion here, so this area is described as not allowing coupled motion. In contrast, other regions like the C1–C2 complex and the thoracic spine show clear coupling patterns due to their facet orientations and joint mechanics. So the occiput is the area lacking that coupled motion.