Longitudinal section of the head and neck showing the anatomical relation of the dens (labeled odontoid process of axis). Clivus is the inferior part of the slope at top left, the upper part of the slope belongs to the sphenoid bone.
The clivus is an important landmark for checking for anatomical atlanto-occipital alignment; the clivus, when viewed on a lateral C-spineX-ray, forms a line which, if extended, is known as Wackenheim's clivus line. Wackenheim's clivus line should pass through the dens of the axis or be tangential to it.
^McKenna DA, Roche CJ, Lee KW, Torreggiani WC, Duddalwar VA. Atlanto-occipital dislocation: case report and discussion. Can J Emerg Med 2006; 8(1):50-3. Available at: link and link. Accessed on: December 7, 2006.