How many thoracic spinal nerves are there, and what do they control?

• A. 10 thoracic nerves; upper body and GI function
• B. 12 thoracic nerves; upper body and GI function
• C. 14 thoracic nerves; upper body function only
• D. 8 thoracic nerves; lower body and GI function

Answer: (B)

There are 12 thoracic spinal nerves, labeled T1 through T12. Each pair emerges at its corresponding thoracic level and provides somatic innervation to the chest wall and intercostal muscles, as well as sensory input from the skin there. In addition, they contribute to autonomic pathways via the sympathetic nervous system, which influences visceral organs, including parts of the gastrointestinal tract. So these nerves are involved in controlling functions of the upper body and, through autonomic fibers, aspects of GI function. That’s why the best answer states 12 thoracic nerves and describes their control as covering both the upper body and GI function.