What is the name of the first cervical vertebra?

The first cervical vertebra is the atlas.

The atlas is the C1 vertebra, the topmost bone of the spinal column. It supports the skull and forms joints with the occipital bones at the base of the cranium. Unlike most vertebrae, it has no conventional vertebral body and no prominent spinous process. Instead, it is shaped mainly by anterior and posterior arches joined to broad lateral masses.

The joints between the atlas and skull are called atlanto-occipital joints. They allow much of the head’s forward-and-backward “yes” motion. The atlas also connects below with the axis, or C2 vertebra. The axis has a tooth-like projection called the dens, around which the atlas and skull rotate, producing much of the head’s side-to-side “no” motion.

The name comes from Atlas, the figure in Greek mythology traditionally described as bearing the heavens. The word was chosen because this vertebra supports the head. Common mix-ups include calling C1 the axis or confusing it with C7, the lowest cervical vertebra; C7 is notable for its relatively long spinous process and is often called the vertebra prominens.