On the first cervical vertebra, the atlas, the whole head rests with only 2 very small joint surfaces to the occiput.
The second cervical vertebra protrudes into the first cervical vertebra with one tooth.
The segments C0/ C1 as well as C1/ C2 are also called head joints or upper cervicals.
When leaving the skull through the foramen magnum, the spinal cord must pass through the atlas and axis first of all.
Malpositions of the occipital bone (forward head position) and malpositions of the atlas and axis exert pressure on the spinal cord and thereby reduce the signal quality of the nervous system.