Development and growth of the craniocervical junction with special reference to topographical relationship between the occipital basion, the anterior arch of atlas, and the odontoid process of axis: A study using human fetuses

The embryonic occipital bone and odontoid process of the axis are attached and connected by the notochord, but become separated in later development and growth. With special attention to the process of separation, we examined sagittal sections of the craniocervical junction in 18 human fetuses at 8–16 weeks and 22 fetuses at 31–37 weeks. At 8–9 weeks, the anterior arch of atlas was always seen overriding the occipital basal part. The odontoid...