Congenital Odontoid Abnormalities
Ossification
Atlas
Three 1° Ossification centres
- two lateral masses with posterior arch in between
- anterior arch which appears at 1 year
- posterior arch fuses at 4 years
- anterior & posterior fuses to body at 7 years
Axis
Five 1° Ossification centres
- two neural arches / lateral masses
- two 1/2 dens
- body
Five 2° Centres