BiologyCoachOnlineBlog

The Atlas and Axis represent the first and second (or C1 & C2 respectively) cervical vertebrae in the human backbone (or vertebral column). The Atlas (C1) is so named because the whole of the skull rests on it. [Think of the image of the Titan Atlas holding up the world in Greek mythology.] The occipital condyles (of the skull) articulate with the superior facets (of the Atlas) thereby connecting the skull to the vertebral column. The Axis (C2) allows you to turn your head from side to side. This is accomplished by the presence of a projection (of the Axis) known as the odontoid process (or Dens). The Dens, then, establishes the pivot on which the Atlas (and thus the skull) rotates. This joint (formed between C1 & C2) is known as the atlanto-axial joint. [The illustration identifies the basic anatomic features of C1 & C2. The relationship between the cervical vertebrae and the skull are shown in the inset illustration.]

Injuries at the level of C2 are relatively common and may even include fractures of the odontoid process (Dens). Such injuries are often the result of automoile accidents. Suspected injuries of the atlanto-axial joint are addressed through immobilization via a cervical collar or Halo brace.