Regarding ossification of the axis vertebra, the secondary centre for the apex (tip) of the odontoid process:
- A Appears at approximately 2 years and fuses with the dens by 12 years ✓
- B Appears at birth and fuses with the dens by 5 years
- C Appears at 6 years and fuses at skeletal maturity at 18 years
- D Is absent in most individuals and represents a persistent synchondrosis
Correct answer: A. Appears at approximately 2 years and fuses with the dens by 12 years
Explanation
The odontoid process forms from two primary centres that unite in utero, and the subdental synchondrosis below it closes between 3 and 6 years. The separate centre for the apex of the dens appears around 2 years of age and unites with the rest of the odontoid by about 12 years. Before fusion it may mimic a fracture, an important radiographic pitfall in children with neck trauma.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.