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Let’s start our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.

Play USMLE Audio MP3  61 14 Neuro control of Respiration Below

Begin 61 14 Neuro control of Respiration Transcription

Moving now to respiratory control. In order to function, the respiratory muscles need electrical stimulation from the central nervous system.

What motor nerve innervates the diaphragm? It starts with a P.

• Phrenic nerve innervates the diaphragm

In what part of the brain is the involuntary rhythm of respiration generated? It starts with an M.

• In the Medulla

Two groups of neurons in the medulla discharge in phase during respiration to generate the basic rhythm of breathing. What are the names of these two groups of cells? Their acronyms are DRG and VRG.

• The dorsal respiratory group and the ventral respiratory group

Which of these two neuron groups is thought to be the main rhythm generator?

• The dorsal respiratory group is thought to be the main rhythm generator

The dorsal respiratory group and the ventral respiratory group are influenced by activity in four other regions of the brain. List these four brain areas alphabetically. I’ll cue you with the first letter or letters of each.

First, CC-

• cerebral cortex

Second, P

• Pons

Third, RAS

• reticular activating system

And fourth T

• thalamus

Is the dorsal respiratory group primarily inspiratory, expiratory, or both?

• The DRG is mainly inspiratory.

The dorsal respiratory group is part of the nucleus of what medullary fiber bundle? The two word answer starts with ST.

• Solitary tract

Afferent information comes into the DRG via what two nerves? They start with the letters V and G.

• The vagus and the glossopharyngeal nerves

The ventral respiratory group is a long column of neurons.

Where in the medulla is the VRG located?

• The VRG is located in the ventral lateral medulla

When do the neurons of the VRG discharge action potentials?

• Some of the VRG neurons discharge during inspiration and some during expiration.

Student doctor, please pause the tape and summarize what we’ve discussed about the DRG and the VRG, the dorsal respiratory group, and the ventral respiratory group.

• In order to function, the respiratory muscles need electrical stimulation from the central nervous system. The phrenic nerve innervates the diaphragm. The involuntary rhythm of respiration is generated in the medulla of the brain. Two groups of neurons in the medulla discharge in phase during respiration to generate the basic rhythm of breathing. They are the dorsal respiratory group, DRG, and the ventral respiratory group, VRG. The dorsal respiratory group is thought to be the main rhythm generator. The DRG and the VRG are influenced by activity in four other regions of the brain- the cerebral cortex, the pons, the reticular activating system, and the thalamus. The DRG is mainly inspiratory. The DRG is part of the nucleus of the solitary tract. Afferent information comes into the DRG via the vagus and the glossopharyngeal nerves. The ventral respiratory group is a long column of neurons found in the ventral lateral medulla. Some of the VRG neurons discharge during inspiration and some during expiration.

 

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