The odontoid is derived from mesenchyme of the first cervical vertebra. During development, it becomes separated from the atlas and fuses with the axis.

The apex, or tip, of the odontoid is derived from the most caudal occipital sclerotome, or proatlas.

This separate ossification center is  called ossiculum terminale, appears at age 3 years and fuses by age 12 years.

Blood Supply Of Odontoid

Vertebral and carotid arteries form the main source of blood supply to odontoid. Anterior ascending artery and  posterior ascending artery  are branches of vertebral artery beginning at the level of C3. They ascend anterior and posterior to the odontoid and meet  superiorly to form an apical arcade.

Cleft perforators come fron of the extracranial internal carotid artery and supply the superior portion of the odontoid.