Thoracic Vertebrae

This chapter describes variations in the anatomy of human thoracic spinal vertebrae with differing degrees of clinical relevance. Although thoracic vertebrae tend to be relatively more uniform than cervical vertebrae, a number of morphologic variations have been characterized. In early embryonic development, all vertebrae possess primordial costal projections and consequently have the potential for rib formation. A limbus vertebra occurs when, in an immature skeleton, a fragment of the nucleus pulposus herniates through the ring hypophysis before fusion has occurred. The process of segmentation may fail to occur in the thoracic spine. There is significant variability in pedicle shape and size between individuals and between thoracic vertebral levels within individuals. The transverse processes of the thoracic vertebrae may fail to ossify, resulting in an appearance that could be confused with a fracture of the tip of the transverse process on a radiograph.