Unlike every other vertebra in your spine, the atlas has a completely different structural design:
First Cervical Vertebra - an overview | ScienceDirect Topics atlas vertebra
The (C1) is the topmost bone of your spine and acts as the literal bridge between your skull and the rest of your body. Named after the Greek Titan Atlas—who was condemned to hold up the heavens—this small, two-ounce bone supports the entire weight of your head, which typically ranges from 8 to 12 pounds. Unique Anatomy & Function Unlike every other vertebra in your spine, the