Apical ligament

The apical ligament is a small ligament that joins the apex (tip) of the dens of C2 to the anterior margin (basion) of the foramen magnum. It is the weak, fibrous remnant of the notochord and does not contribute significantly to stability.

The more posterior alar and cruciate ligaments are stronger and therefore far more clinically significant. Anterior is the anterior atlanto-occipital membrane.

Variant anatomy

It may be absent in up to 20% .