Figure 3From: Cervical myelopathy caused by atlantoaxial instability in a patient with an os odontoideum and total aplasia of the posterior arch of the atlas: a case report Computed tomography images of the cervical spine. (A) Complete absence of the posterior arch of the atlas with an anterior cleft was observed. (B) The sagittal plane of the three-dimensional computed tomography scan shows the os odontoideum.Back to article page