The craniocervical junction: embryology, anatomy, biomechanics and imaging in blunt trauma

Imaging of the blunt traumatic injuries to the craniocervical junction can be challenging but central to improving morbidity and mortality related to such injury. The radiologist has a significant part to play in the appropriate management of patients who have suffered injury to this vital junction between the cranium and the spine. Knowledge of the embryology and normal anatomy as well as normal variant appearances avoids inappropriate investigations in these trauma patients. Osseous injury can be subtle while representing important radiological red flags for significant underlying ligamentous injury. An understanding of bony and ligamentous injury patterns can also give some idea of the biomechanics and degree of force required to inflict such trauma. This will assist greatly in predicting risk for other critical injuries related to vital neighbouring structures such as vasculature, brain stem, cranial nerves and spinal cord. The embryology and anatomy of the craniocervical junction will be outlined in this review and the relevant osseous and ligamentous injuries which can arise as a result of blunt trauma to this site described together. Appropriate secondary radiological imaging considerations related to potential complications of such trauma will also be discussed. TEACHING POINTS • The craniocervical junction is a distinct osseo-ligamentous entity with specific functional demands. • Understanding the embryology of the craniocervical junction may prevent erroneous radiological interpretation. • In blunt trauma, the anatomical biomechanical demands of the ligaments warrant consideration. • Dedicated MRI sequences can provide accurate evaluation of ligamentous integrity and injury. • Injury of the craniocervical junction carries risk of blunt traumatic cerebrovascular injury.