Axis (anatomy) The condition, where the dens is separated from the body of the axis, is called os odontoideum, and may cause nerve and circulation compression syndrome. On its anterior surface is an oval or nearly circular facet for articulation with that on the anterior arch of the atlas. On the back of the neck, and frequently extending on to its lateral surfaces, is a shallow groove for the transverse atlantal ligament which retains the process in position. The apex is pointed, and gives attachment to the apical odontoid ligament; below the apex the process is somewhat enlarged, and presents on either
Axis (anatomy) vertebrae The spinous process is large, very strong, deeply channelled on its under surface, and presents a bifurcated extremity. Contact sports are contraindicated for individuals with an anomalous dens, as any violent impact may result in a catastrophic injury. This is because a malformed odontoid process may lead to instability between the atlas and axis (the C1 and C2 cervical vertebrae). The axis is ossified from five primary and two secondary centers. The body and vertebral arch are ossified in the same manner as the corresponding parts in the other vertebrae, viz., one center for the body, and two for