Abnormal spicules on the inferior aspect of anterior arch of atlas vertebra.

Anterior arch of the atlas vertebra is known to exhibit various developmental anomalies. Bony outgrowths, osteophytes, clefts and aplasia of the anterior and posterior arches of the atlas have received special attention by research workers. To the best of our knowledge, not many osteological studies have defined the spicules on the anterior arch of the atlas. The present study describes an abnormal atlas vertebra with 2 spicules on the inferior aspect, 2 additional facets inferior to the superior articular facets and a peculiar facet to the left of the posterior tubercle. These abnormal spicules may cause dysphagia or involve atlanto-occipital movements. Such anomalies may be misinterpreted in routine X rays as a degenerative disease. However, asymptomatic cases remain undetected throughout life. Such anomalies may be important in radiological, clinical, forensic and anthropological studies.