ABSTRACT
Background: Hypermobility of Atlanto-Occipital joints give rise to symptoms related to vascular compromise viz syncope, vertigo, transient impairment of visual field, altered consciousness. Surgical management of congenital anomalies of craniovertebral junction requires a precise identification of underlying pathophysiological condition. For this reason variation in superior articular facets of atlas vertebrae in terms of its morphology should be known. Method: The morphology of 100 atlas vertebrae had been studied and observations of total 200 facets were noted. Measurements were taken with a vernier callipers and a compass. Result :In the present study, typical oval, elongated or kidney shaped outline was found in 74.5% facets. Constrictions or notches were present on 48% facets. Complete separation (4.5%) is suggestive of tendency towards possible restriction of movement at atlanto-occipital joint as part of evolutionary changes. Roughly circular pressure facets had been observed in 78% of vertebrae indicating possibly greater pressure at this site during movement at atlanto-occipital joint.Conclusion: Knowledge of this variation in craniovertebral junction is of significant importance for Neurosurgeons and Orthopaedic surgeons doing various surgeries in this region.