=====Opisthion=====
The opisthion is the median (midline) point of the posterior margin of the [[foramen magnum]].

{{::opisthion.png?300|}}

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



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

Powers ratio

Boogards angle

[[McRae’s line]]

Chamberlain line