Abnormal foramina on the posterior arch of atlas vertebra

Atlas is the first cervical vertebra. It articulates with the occipital bone above and the axis vertebra below. It plays an important role in movement of the skull and the neck. We found a rare variation of the atlas vertebra. The posterior arch of the atlas had one accessory foramen just behind each lateral mass. Foramen on the right side was larger than that of the left. The knowledge of this variation may be of importance to orthopedic surgeons, neurosurgeons, radiologists and anthropologists.