The C5 and C6 vertebrae are two of the bones that make up the upper part of the spinal column, the bony structure that keeps the upper body upright and protects the spinal cord. The spine is broken up into three different sections: the cervical spine, the thoracic spine, and the lumbar spine. The C5 and C6 vertebrae are cervical vertebrae, which are at the top of the spinal column closest to the head.