C3,4,5 keep the diaphragm alive (i.e. the phrenic nerve) and irritation of the diaphragm can cause referred pain to the left shoulder due to C5 (FA2020 p663).
Phrenic nerve- C3,C4,C5(supply diaphragm)
Suprascapular nerve- C3,4(supply shoulder)
Thus, referred pain.
submitted by โcassdawg(1781)
C3,4,5 keep the diaphragm alive (i.e. the phrenic nerve) and irritation of the diaphragm can cause referred pain to the left shoulder due to C5 (FA2020 p663).