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Ventral respiratory group

The ventral respiratory group (VRG) is a column of neurons located in the ventrolateral region of the medulla, extending from the caudal facial nucleus to −400μm obex.The ventral respiratory group is one of the respiratory groups in the respiratory centre. The four groups of neurons of the VRG are the rostral retrofacial nucleus, caudal nucleus retroambiguus, nucleus paraambiguus, and the pre-Bötzinger complex.

Respiratory effects

The VRG contains both inhalation (inspiratory) and exhalation (expiratory) neurons. The VRG appears to be a rhythm generating and integrative center. When its inspiration neurons are fired, a burst of impulses travels along the phrenic nerve which excites the diaphragm and the intercostal nerve which excites the external intercostal muscle. This leads to expansion of the thorax and air rush into the lungs. When VRG expiratory neurons fire, the output stops, and expiration occurs passively, as the inspiration muscles relax and the lungs recoil.

The two respiratory groups in the medulla – the ventral and the dorsal respiratory group are responsible for the control of the rhythm of respiration.[1]


  1. ^ Tortora, Gerard (2011). Principles of anatomy and physiology (13th ed.). Hoboken, N.J.: Wiley. pp. 905–909. ISBN 978-0-470-64608-3.

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