thoracic spinal nerve 5 thoracic spinal nerve 5 the thoracic spinal nerve 5 (t5) is a spinal nerve of the thoracic segment. thoracic spinal nervethe spinal cord with spinal nerves.detailsidentifierslatinnervi spinalisfma6293anatomical terminology it originates from the spinal column from below the thoracic vertebra 5 (t5).