The vertebra without vertebrae in the human body is the atlas, which is located at the top of the spine, the first cervical vertebra, and is connected to the occipital bone above it, and is anatomically characterized by the absence of vertebrae. A typical vertebra consists of four parts, namely the vertebral body, the vertebral arch, the spinous processes and transverse processes, and the articular process, and the atlas is the only one of these vertebrae that does not have a vertebral body. The atlas is located at the top of the spine, the first cervical vertebra, and is attached to the occipital bone at its upper end. It is annular in shape, has no vertebral body, and consists of the anterior and posterior arches and two lateral blocks. In newborns, the atlas is composed of two blocks, and as the baby ages, the incomplete posterior arch on both sides gradually ossifies to form a complete posterior arch. The atlantoaxial spine is anatomically important in the human body. Damage to the atlantoaxial spine can have serious consequences, even life-threatening, and atlantoaxial instability is one of the more common clinical disorders. If atlantoaxial discomfort occurs, it is necessary to go to a regular hospital as soon as possible to avoid delaying the condition.