Epistrophy: What is it? Anatomy, Ossification, Function and Pathologies

Joined to the atlas (first cervical vertebra) through the atlantoaxial articulation, the axis is a very particular vertebra; it, in fact, has a small vertebral body, from which a prominence originates on the upper side called tooth, which is absent in all the other vertebrae of the spinal column.
Thanks to the tooth, the axis acts as a pivot of rotation for the atlas: this mechanism allows the human being to turn the neck and head with greater ease.
Together with the atlas, the axis constitutes the segment of the cervical spine most subject to fracture; the fracture of the axis is a much feared injury, because it can lead to permanent paralysis or, in the most unfortunate cases, to the death of the victim.