Axis is the name for:

Second cervical vertebra (axis) Presence of odontoid process. Transverse processes are small and lack the anterior tubercle. Anterior margin of the inferior surface of the body projects downwards to a considerable extent. Foramen transversarium is directed superolaterally (expand in typical vertebrae it is directed vertically) Inferior surface presents a deep and wide inferior vertebral notch placed in front of the inferior articular process. The superior vertebral notch is shallow and is present behind the superior articular process. Key concept: Second cervical vertebra is called the axis. it is identified by the presence of the dens or odontoid process which is a strong, tooth-like process projecting upwards from the body. The dens is usually  believed to represent the centrum or body of the atlas which has fused with the centrum of the axis.