MATERIAL and METHODS: Cranial and cervical magnetic resonance images including occiput, C1, and C2, and those obtained for different reasons such as evaluation of cranial and upper cervical pathology were re-evaluated for this study. Synchondroses around the odontoid process were accepted as the boundaries between the neural arch and the body of C2.

RESULTS: Thirty cases were included for this study. Fifteen of these were adult cases and the remaining 15 were in pediatric cases. Apicodental, dentocentral, neurocentral, and dentoneural synchondrotic articulations were clear, especially under the ages of 3 years. The dentocentral synchondrosis was found well below the line drawn through the level of superior articulating facets.

CONCLUSION: This study demonstrated that the inferior boundary of the odontoid process is not located at the level of superior articulating facets. The real border between the odontoid process and the body of C2 is located well below the level of the superior articulating facets because of the location of the dentocentral synchondrotic articulation. This level should be considered in the classification of C2 fractures. Keywords : Odontoid process, Dentocentral synchonrosis, The boundaries of the odontoid process