ABSTRACT
The spinal transitional zones (TZs) are located at the junction of two adjacent spinal regions with various differences in posterior element orientation and differing degrees of mobility. There are four TZs, top to bottom (Fig. 61.1): cervico-occipital (CO), cervicothoracic (CT), thoracolumbar (TL), and lumbosacral (LS). While they may differ significantly, vertebrae of the same region (cervical, thoracic, or lumbar) have common characteristics. Vertebrae of a junction or TZ have intermediate characteristics.
