Severing the nerves that innervate the breathing muscles may lead rapidly to death. Will a spinal cord break between the level of cervical vertebrae 6 and 7 leave the victim able to breathe? Choose the answer with the correct reason. A. No. The breathing muscles are innervated by spinal nerves that leave the spinal cord at the level of each thoracic vertebra. B. Yes. The diaphragm will work as it is innervated by nerves arising from C3 to C5. C. No. The breathing muscles are innervated by autonomic impulses from the respiratory centre which is located in the brain stem. D. Yes. The muscles of breathing are innervated by the sympathetic nervous system which is unaffected by damage to the somatic nervous system.
Option B. The diaphragm, however now no longer the intercostal muscle will still receive innervation because the diaphragmatic nerves depart the spinal cord superior to the break at C6–C7.
