Quoc: The atlas is the topmost vertebra and with the axis forms the joint connecting the skull and spine. The atlas and axis are specialized to allow a greater range of motion than normal vertebrae. They are responsible for the nodding and rotation movements of the head.

Answer this question based on the passage: what bone allows the head to nod yes?
HW Chung: OK, some thoughts:
The relevant information is: They are responsible for the nodding and rotation movements of the head. The answer is atlas and axis.