The axis is the second cervical vertebra. It has an odontoid process, or dens, which is a tooth-like protrusion, lined with cartilage, which articulates with the atlas on top. The atlas, together with the skull turns about the odontoid process as if it were an axis, hence the name. The anterior aspect of the odontoid process bears an anterior articular facet for articulation with the facet for the dens of the first cervical vertebra. Meanwhile, the posterior side of the axis dens has a posterior articular facet, on which the transverse ligament of the atlas adjoin.
At the base of the transverse process on both lateral aspects, the second cervical vertebra bears a superior articular facet, which is for the articulation with the inferior articular facet of first cervical vertebra (atlas). Like the other vertebrae, the axis has a transverse foramen in each transverse process. In the cervical portion of vertebral column, this orifice is for the vertebral artery and vein. On the posterior aspect of its body, it has a short spinous process; the rectus capitis posterior major and the obliquus capitis inferior muscle are attached to the spinous process of the axis.
Below, lateral view of second cervical vertebra, with their different parts
