|Brain: Dorsal respiratory group
| Section of the medulla oblongata at about the middle of the olive. (Dorsal respiratory group not labeled, but spinal tract labeled at center right.)
Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
The dorsal respiratory group (DRG) is located in the dorsomedial region of the medulla, and is composed of cells in the solitary tract nucleus. The DRG is found in many types of fish and mammals.
The DRG is involved in the generation of respiratory rhythm, and is primarily responsible for the generation of inspiration. It is a part of the solitary tract, which is responsible for appropriating responses to sensory information from chemoreceptors and mechanoreceptors in humans.
Inspiration begins when cells of the solitary tract nucleus (along with cells of the ventral respiratory group) begin a steady increase in firing, leading to contraction of the respiratory muscles. When neurons in the DRG fire, impulses travel down the phrenic and intercostal nerves to stimulate the diaphragm and external intercostal muscles. The thoracic cavity expands and air rushes into the lungs due to the negative pressure, producing inspiration. When the cells stop firing, the inspiratory muscles relax, inspiration ceases, and exhalation begins.
The rhythm of the DRG produces a respiratory rate of 12-16 breaths per minute in humans. Inspiration usually lasts approximately 2 seconds, and expiration lasts about 3 seconds. The normal inspiration rate and rhythm is called eupnea, and difficult respiration is termed dyspnea.
Berne, Robert M.; Levy, Matthew N.;Koeppen, Bruce M.;Stanton, Bruce A. (2004). Physiology, 5th edition. St. Louis, MO: Elsevier, 513. ISBN 0-323-03390-3.
|Brain: rhombencephalon (hindbrain)|
anterior/ventral: Arcuate nucleus of medulla • Pyramid (Decussation) • Olivary body • Inferior olivary nucleus • Anterior median fissure • Ventral respiratory group
posterior/dorsal: VII,IX,X: Solitary/tract • XII, X: Dorsal • IX,X,XI: Ambiguus • IX: Inferior salivatory nucleus • Gracile nucleus/Cuneate nucleus/Accessory cuneate nucleus • Area postrema • Posterior median sulcus • Dorsal respiratory group
raphe/reticular: Sensory decussation • Reticular formation (Gigantocellular nucleus, Parvocellular reticular nucleus, Ventral reticular nucleus, Lateral reticular nucleus, Paramedian reticular nucleus) • Raphe nuclei (Obscurus, Magnus, Pallidus)
tracts: Corticospinal tract (Lateral, Anterior) • Inferior cerebellar peduncle • Olivocerebellar tract • Spinocerebellar (Dorsal, Ventral) • Spinothalamic tract • PCML (Posterior external arcuate fibers, Internal arcuate fibers, Medial lemniscus) • Extrapyramidal (Rubrospinal tract, Vestibulospinal tract, Tectospinal tract)
anterior/ventral: Superior olivary nucleus • Basis pontis (Pontine nuclei, Middle cerebellar peduncles)
posterior/dorsal: Pontine tegmentum (Trapezoid body, Superior medullary velum, Locus ceruleus, MLF, Vestibulocerebellar tract, V Principal Spinal & Motor, VI, VII, VII: Superior salivary nucleus) • VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior)
raphe/reticular: Reticular formation (Caudal pontine reticular nucleus, Oral pontine reticular nucleus, Tegmental pontine reticular nucleus, Paramedian pontine reticular formation) • Median raphe nucleus
Apneustic center • Pneumotaxic center
|Metencephalon/cerebellum||Vermis • Flocculus • Arbor vitae • Cerebellar tonsil • Inferior medullary velum|
Molecular layer (Stellate cell, Basket cell, Parallel fiber) • Purkinje cell layer (Purkinje cell) • Granule cell layer (Golgi cell) • Mossy fibers • Climbing fiber
Deep cerebellar nuclei (Dentate, Emboliform, Globose, Fastigial)
|Fourth ventricle||apertures (Median, Lateral) • Rhomboid fossa (Vagal trigone, Hypoglossal trigone, Obex, Sulcus limitans, Facial colliculus, Medial eminence) • Lateral recess|