Phrenic Cross Innervation of the Hemidiaphragm in the Dog

¹ From the Department of Gastro-Intestinal Research, Medical Research Institute, Michael Reese Hospital, Chicago, Illinois

In acute experiments on mongrel dogs, the innervation of each hemidiaphragm was investigated. In approximately 30% of the animals a division of the posterior branch of the left phrenic nerve was found to cross to the right side, innervating part of the right crus of the diaphragm immediately to the right of the esophageal hiatus. A similar cross innervation from right to left was not found; neither was a cross innervation from an anterior branch of the phrenic nerve found. The physiologic significance of cross innervation in relation to trophic maintenance of the muscle of the diaphragm by sympathetic innervation is discussed.