Which statement best describes the relationship between spinal injury level and diaphragmatic function?

Which statement best describes the relationship between spinal injury level and diaphragmatic function?

• A. Injury at or below C3 always preserves diaphragmatic function
• B. Injury above C6 may cause diaphragmatic paralysis
• C. Injury above C6 never affects breathing
• D. Injury at C7 only affects leg movement

Answer: (B)

Diaphragmatic function depends on the phrenic nerve, which arises from spinal cord segments C3 to C5. When a spinal injury is at a high cervical level, above these nerve roots, the brain’s commands to the diaphragm can be cut off, leading to diaphragmatic paralysis and serious breathing problems. That’s why injuries above the C6 level can cause diaphragmatic paralysis—their signals to the phrenic motor neurons are disrupted, so the diaphragm may stop functioning properly. The other statements aren’t accurate: injuries at higher levels don’t guarantee preserved diaphragmatic function, and saying such injuries never affect breathing ignores the well-established role of high cervical injury in compromising respiration. Also, an injury at a level like C7 isn’t limited to leg movement; depending on the exact pathways involved, diaphragmatic control can be affected as well.

Diaphragmatic function depends on the phrenic nerve, which arises from spinal cord segments C3 to C5. When a spinal injury is at a high cervical level, above these nerve roots, the brain’s commands to the diaphragm can be cut off, leading to diaphragmatic paralysis and serious breathing problems.

That’s why injuries above the C6 level can cause diaphragmatic paralysis—their signals to the phrenic motor neurons are disrupted, so the diaphragm may stop functioning properly. The other statements aren’t accurate: injuries at higher levels don’t guarantee preserved diaphragmatic function, and saying such injuries never affect breathing ignores the well-established role of high cervical injury in compromising respiration. Also, an injury at a level like C7 isn’t limited to leg movement; depending on the exact pathways involved, diaphragmatic control can be affected as well.