Final answer:
The occipital condyles articulate with the atlas (C1 vertebra) at the atlanto-occipital joint, allowing for flexion and extension of the head.
Step-by-step explanation:
The occipital condyles articulate with the atlas (C1 vertebra). These articulations form the atlanto-occipital joint, which allows the skull to rock forward and backward, producing flexion and extension of the head.