Anatomy: Located in each side of the medulla, about 5 millimeters anterior and lateral to the dorsal respiratory group of neurons (in the nucleus ambiguous rostrally and the nucleus retroambiguus caudally).
Function:
almost totally inactive during normal quiet respiration.
When the respiratory drive becomes greater than normal → VRG activate by oscillating mechanism of the DRG → inspiration;
VRG can generate signals to the abdominal muscles → heavy expiration.