Last revised by Craig Hacking on 7 Oct 2017

The basion is the median (midline) point of the anterior margin of the foramen magnum. The apical ligament attaches to it.

It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement.

Clinical importance

Various lines and measurements using the basion are made in the diagnosis of atlanto-occipital dissociation (AOD) injuries, platybasia and basilar invagination:

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