thoracic spinal nerve 9 thoracic spinal nerve 9 the thoracic spinal nerve 9 (t9) is a spinal nerve of the thoracic segment. thoracic spinal nervethe spinal cord with spinal nerves.detailsidentifierslatinnervi spinalisfma6306anatomical terminology it originates from the spinal column from below the thoracic vertebra 9 (t9).