Eur J Anat, 12 (3): 159-167 (2008)

Occipitalization of atlas with other associated anomalies of skull

Sharma M., Singh B., Abhaya A., Kumar H.

Department of Anatomy, Govt. Medical College and Hospital, Sector-32, Sarai Building, Chandigarh-160030, India; Department of Anatomy, Vardhman Mahavir Medical College, New Delhi, India

ABSTRACT Congenital fusion of the atlas with the occipital bone is the common denominator of a galaxy of skull defects. Some skull anomalies may result in sudden unexpected death. Seventy dry skulls were obtained from the Department of Anatomy. Of these, 2 skulls showed occipitalization. These were photographed and radiographed. Several measurements, including cranial index, dimensions of the foramen magnum, basal angle and basal impression, were taken. Both skulls showed near by complete fusion of the atlas with the occipital bone. A continuation of the confluence of the sinuses only to the left transverse sinus was observed in both skulls. One skull was asymmetrical in shape. The foramina transversaria of atlas in this specimen were bilaterally reduced to admit only the diameter of a safety pin. The thickness of the wall of the other skull was asymmetrical on the two sides. It also showed a shelf-like bony triangular projection (dural band/spur), which was attached to the upper margin of the groove for the transverse sinus on the right side. The cranial indices of both the skulls were greater than 80 (brachycranial/brachycephalic). Basal angles were within the normal range (120°-140°). These variations are discussed in light of developmental aspects and their clinical significance.

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