The vertebral column, or spinal column, is made up of a total of 33 vertebrae, which are subdivided into five regions: cervical, thoracic, lumbar, sacral, and coccyx. At the cervical region the spinal column is further classified into an upper and lower cervical region. The atlas is one of the two upper cervical vertebrae, also known as C1, which is the topmost vertebra of the spinal column. It is the vertebra that is in contact with the occipital bone, a flat bone located at the back portion of the head.

This first cervical bone is named from the mythical Greek god who carried the world on his shoulders, as its function is to support the globe of the head. Together with the second vertebra, the axis, it is responsible for the wide range of motion of the head.

The atlas does not look like a typical vertebra, with its ring-like structure and the absence of a body, which is actually fused to the axis. Other anatomical landmarks on the atlas include the anterior arch and tubercle, posterior arch and tubercle, vertebral notches, facets, and transverse processes.