The thoracic spine consists of the 12 vertebrae between your neck and lower back. The ends of your ribs, although not attached to the spine, rest in indentations in the thoracic vertebrae that help support the ribs. This arrangement also makes the thoracic vertebrae more stable than other vertebrae. Disc herniation in the thoracic spine is relatively rare compared to the lumbar vertebrae in the lower back and the cervical vertebrae in the neck. Thoracic disc herniations account for less than 1 percent of all protruded discs.