Final answer:
The specific joint between the skull and the spine that permits nodding is called the atlanto-occipital joint. This joint allows the skull to rock forward and backward, producing flexion and extension of the head.
Step-by-step explanation:
The specific joint between the skull and the spine that permits nodding is called the atlanto-occipital joint. This joint is formed by the articulations between the superior articular processes of the atlas (C1 vertebra) and the occipital condyles on the base of the skull. The atlanto-occipital joint has a U-shaped curvature, allowing the skull to rock forward and backward, producing flexion and extension of the head.