Occipitalization of Atlas.

ABSTRACT

Occipitalization of atlas is an osseous anomaly of the craniovertebral junction which occurs at the base of the skull in the region of the foramen magnum. The knowledge of such a fusion is important because skeletal abnormalities at the craniocervical junction may result in sudden death. During bone cleaning procedure and routine undergraduate osteology teaching, three skulls with Occipitalization of atlas were encountered in the department of Anatomy atMMIMSR,Mullana, India. In one skull, both anterior and posterior archwere completely fused with occipital bone while the transverse process on the right side was not fused whereas left transverse process was fused with occipital bone. Both anterior and posterior arch were completely fused whereas transverse process on both sides were not fused in other skull. In another skull, partial and asymmetrical Occipitalization of atlas vertebra with occipital bone was found with bifid posterior arch of atlas at the level of posterior tubercle. Anterior arch was completely fused with basilar part of occipital bone but both the transverse processes were not fused. Reduced diameter of foramenmagnum due to the atlanto-occipital fusion might cause neurological complications due to compression of spinal cord or medulla oblongata, vertebral vessels, 1st cervical nerve, thus, knowledge of occipitalization of the atlas may be of substantial importance to orthopaedicians, neurosurgeons, physicians and radiologists dealing with abnormalities of the cervical spine.