Final answer:
There are twelve pairs of thoracic spinal nerves, coinciding with the twelve thoracic vertebrae, and these nerves lead to the intercostal nerves between the ribs.
Step-by-step explanation:
There are twelve (thoracic pairs of spinal nerves, specifically designated as T1 to T12. These spinal nerves emerge from the spinal cord and correspond to the twelve thoracic vertebrae in the upper back, known as Th1 to Th12. Each nerve pair exits the spinal column through the intervertebral foramen near its corresponding vertebra. The thoracic nerves give rise to the intercostal nerves that run between the ribs, which are part of the thoracic cage structure consisting of 12 pairs of ribs and the sternum. Unlike some of the spinal nerves in other regions of the spine, the thoracic spinal nerves T2 through T11 do not form part of larger nerve plexuses but directly innervate the intercostal spaces.