DRG
This medullary region contains mostly inspiratory neurons, particularly active during quiet breathing.
The Dorsal Respiratory Group (DRG).
The VRG's motor output to expiratory and accessory muscles is largely inactive during this type of breathing.
Quiet/resting breathing.
This larger respiratory group, located in the medulla, contains the pre-Bötzinger complex embedded within it.
Ventral respiratory group (VRG).
This is the overall role of the pontine respiratory group.
Switching between inspiration and expiration to control rate and depth.
This nerve, arising from C3–C5, carries DRG signals to the diaphragm.
Phrenic nerve.
During forced breathing, VRG motor output is recruited for both active expiration AND this other process.
Active/forceful inspiration
Unlike the surrounding VRG motor output neurons, the pre-Bötzinger complex is continuously active for this reason.
Role as the pacemaker for breathing (it must fire for every breath, including at rest).
This center within the PRG stimulates DRG neurons to increase inspiration depth.
Apneustic centre.
DRG signals reach the external intercostal muscles via this set of nerves.
Intercostal nerves.
VRG signals for active expiration travel to the abdominal muscles and this other muscle group.
Internal intercostal muscles
In humans, this is the result of a bilateral lesion of the pre-Bötzinger complex.
Complete respiratory arrest
This center within the PRG inhibits, or "switches off," DRG inspiratory neurons, regulating overall breathing rate.
Pneumotaxic center.
DRG recieves sensory input from the peripheral chemoreceptors and lung mechanoreceptors via these cranial nerves.
CN IX and CN X.
This viral disease, in its bulbar-infecting form, can directly destroy medullary respiratory center neurons. This is a central cause of respiratory failure distinct from the peripheral muscle paralysis of its spinal form, and the reason many childhood victims needed iron lungs.
Poliomyelitis (bulbar polio).
Depression of the pre-Bötzinger complex is a key danger in overdose of this class of drugs.
Opioids.
In this condition, caused by a bilateral lesion of the ventral pons (usually stroke), breathing is typically preserved because the pontine respiratory group sits more dorsally, out of the lesion's reach. Though patients still need ventilatory support initially due to the surrounding injury.
Locked-in syndrome.