A spinal cord injury at the level of C7 would MOST likely result in:

• A. Paralysis of the diaphragm.
• B. Paralysis of the intercostal muscles.
• C. Paralysis of all the respiratory muscles.
• D. Immediate cardiac arrest.

Answer: (B)

A high cervical injury disrupts motor signals to muscles below the lesion, but the diaphragm is controlled by the phrenic nerve from C3–C5, which is above a C7 injury, so the diaphragm can stay functional. Intercostal muscles are innervated by the thoracic nerves (T1–T11); a lesion at C7 interrupts those pathways, leading to paralysis of the intercostal muscles. This impairs chest wall expansion and coughing, while the diaphragm continues to drive breathing, though less efficiently. So the most likely outcome is paralysis of the intercostal muscles. Immediate cardiac arrest is not a typical direct consequence of a C7 spinal cord injury, and paralysis of all respiratory muscles would require involvement of the diaphragm as well, which isn’t expected here.