Third condyle

Last revised by Yaïr Glick on 29 Mar 2022

The third condyle, also known as condylus tertius or median occipital condyle, is a rare anatomic variant of the occipital condyles. It is a small separate ossicle at the anteromedial margin of the occipital condyle formed by the failure of the embryonic proatlas (4th occipital sclerotome) to unite with the condyle proper.

It may form a true arthrosis or pseudoarthorosis with the adjacent odontoid process of the axis or anterior arch of the atlas and has an association with an os odontoideum.

The third condyle is one of several occipital vertebrae variants. Other variants include:

Practical points

This anatomical variant may mimic an occipital condyle fracture.

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Cases and figures

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  • Case 2
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