An axial CT of the upper cervical spine after trauma shows the odontoid process of C2 lying between the anterior arch of C1 and a dense band running horizontally behind it. The band preventing anterior translation of the atlas is the:
- A Anterior atlanto-occipital membrane
- B Alar ligament
- C Transverse ligament of the atlas ✓
- D Posterior longitudinal ligament
Correct answer: C. Transverse ligament of the atlas
Explanation
The transverse ligament of the atlas passes behind the dens, attaching to tubercles on the medial aspect of the lateral masses of C1, and holds the odontoid process against the anterior arch, preventing anterior translation of the atlas. The alar ligaments run from the sides of the dens to the occiput and limit rotation rather than holding the dens in place. The posterior longitudinal ligament lies further posteriorly, lining the vertebral canal.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.