Which spinal levels give rise to the phrenic nerve?

• A. C3-5
• B. C4-6
• C. C2-4
• D. C5-7

Answer: (A)

The nerve that controls the diaphragm comes from the ventral rami of spinal nerves C3 through C5, with C4 providing the main motor contribution. This arrangement is often remembered by the phrase “C3, 4, 5 keep the diaphragm alive.” That makes this set the best answer because it precisely matches the nerve’s embryologic roots and the primary innervation to the diaphragm.

If we consider other ranges, they don’t fit the standard pattern: starting too low and including C6 would add an extra, nonessential level; starting at C2 and ending at C4 would miss C5; ending at C7 would include C7 and miss C3. The phrenic nerve travels from these roots down the neck to the diaphragm, delivering motor input and some sensory fibers to surrounding pleura and pericardium, which is why understanding the root levels helps explain diaphragmatic function and related clinical issues.