In the cervical spine, what is referred to as the atlas?

The atlas refers specifically to the first cervical vertebra, known as C1. It plays a crucial role in supporting the skull, allowing for the nodding motion of the head, and facilitating the connection between the skull and the spine. The structure of the atlas is unique; it lacks a central body, which differentiates it from other vertebrae. Instead, it consists of an anterior and posterior arch and lateral masses, which allow it to accommodate the occipital condyles of the skull. This design enables a range of motion, particularly flexion and extension of the head. The atlas's importance in the cervical spine and its structural characteristics make it a vital component for both stability and mobility in the neck region.