A case of atlanto-occipital fusion with other multiple anatomic variations.

In the routine anatomic measurement study on Asian dry skulls, a skull of atlanto-occipital fusion with other multiple anatomic variations was observed. The entire right half of the atlas vertebra, including the anterior arch, anterior tubercle, posterior arch, and lateral masses, was fused entirely with the occipital bone, while the left fused partly. Besides the atlanto-occipital fusion, the target skull specimen also includes posterior arch defects of the atlas, metopic suture, and wormian bones. So many anatomical variations rarely exist in one specimen. This paper aims to present detailed anatomic case reports and discuss related diseases in an anatomic and clinical study.