Introduction: Estimation of dimensions of the craniovertebral junction is important in the planning of neurosurgical procedures of the posterior cranial fossa. This study aimed at determining the association between the occipital condyles (OC) and foramen magnum (FM) dimensions with the biparietal diameter (BPD) in adult Nigerians.  

Materials and Methods: Brain computed tomography images of 336 adults were retrospectively analyzed in the Radiology department of a Teaching Hospital after obtaining ethical approval. The BPD, OC and FM dimensions were measured and the data analyzed using Statistical Package for Social Sciences version 23 then summarized in means and standard deviations. Pearson’s correlation test was used to establish an association between the measurements and this was considered significant at p <0.05. 

Results: Significant gender differences were observed in the OC and FM measurements. There was also significant correlation between FM and OC widths; FM width and BPD, intercondylar and bicondylar distances; BPD and the intercondylar and bicondylar distances; and lastly the FM length and distance from the anterior tips of the OC to the opisthion (p<0.05).

Conclusion: The significant gender differences in the OC and FM measurements should be considered during the planning of CVJ surgeries. Although significant, the correlations between the OC, FM and BPD dimensions were weak hence the need for preoperative radiologic measurement of these variables by surgeons in the studied population to avoid complications.