Trophic Effects in the Absence of Respiratory Function of the Phrenic Nerve

Abstract

In the dog, section of a phrenic nerve is followed by progressive and finally complete atrophy of the muscle of the hemidiaphragm. If a phrenic nerve is crushed, or cut and reunited by primary anastomosis, no degeneration of the diaphragm is seen, although respiratory function is absent for about 3 months. Likewise, no atrophy of the diaphragm occurs after vagophrenic anastomosis. Therefore, trophic effects may exist in the absence of functional activity and they may be transmitted by another nerve, independent of its original function.