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Old 06-22-2011
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Vascular The role of vagus & glossopharyngeal nerves in Carotid Massage!

can some one explain the role of VAGUS and GLOSSOPHARYNGEAL NERVES in carotid massage?
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Originally Posted by IKR123 View Post
can some one explain the role of VAGUS and GLOSSOPHARYNGEAL NERVES in carotid massage?
Carotid massage will cause stretch of the receptors --> Sends efferent signals via Glossopharyngeal to the brain (NTS), which will then send afferent signals via the vagus to the heart to decrease contract / HR.
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cant understand yet..

WHAT WILL BE EFFECT OF CAROTID MASSAGE ON HEART

Q-bank says following..(sorry for low quality pic)

according to it VAGUS NERVE FIRING SHOULD BE INCREASED BUT Q-BOOK SAYS 9th NERVE firing inc and vagus firing dec..?

The role of vagus & glossopharyngeal nerves in Carotid Massage!-photo2446.jpg
click image to enlarge
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Originally Posted by IKR123 View Post
cant understand yet..

WHAT WILL BE EFFECT OF CAROTID MASSAGE ON HEART

Q-bank says following..(sorry for low quality pic)

according to it VAGUS NERVE FIRING SHOULD BE INCREASED BUT Q-BOOK SAYS 9th NERVE firing inc and vagus firing dec..?
Its simple:

Carotid Efferent (goes to Brain) via Glossopharyngeal N. (IX)

Brain to Heart via Vagus:

Now, when there is increased firing from Carotid Efferent, it is usually done when there is increased stretch of the vessel wall, (increased HR / BP), and this will send the message to the brain via IX, then from brain will decrease firing of Vagus (which goes to heart). This will slow down HR, and DROP the BP.
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Old 06-22-2011
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the Simple way i use always to understand here is that "CAROTID MASSAGE is like "Stresssing" the body which produce a HTA state, so X and IX result in the control of this... so Give the opossite... Decreasing HR = Bradicardia / Hypotension...

remember X = only control High Blood Pressure
IX = Control Both... So....

When you produce by the carotid massage the High Blood pressure the X and IX sense and they act on it... decreasing those...

Pretty much the same as PatelMD said...
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it means vagus nerve stimulation will increase hr and bp and vagus nerve inhibition will decrease hr and bp..?
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Originally Posted by IKR123 View Post
it means vagus nerve stimulation will increase hr and bp and vagus nerve inhibition will decrease hr and bp..?
No, if we selective stimulate the Vagus and Goso will develop Bradicardia and Hypotension. In the same way, if we cut it those nerve pte develop tachycardia and hta.
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Old 06-22-2011
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Hmm, this is quite confusing. Here are a few points that I think we need to clarify (how I think it works).
1. The carotid sinus baroreceptor is innervated by CN IX (not X). Carotid sinus responds to both increase and decrease in blood pressure
2. The aortic arch baroreceptors are innervated by CN X. Aortic arch only responds to increase in blood pressure.

Therefore, the response in carotid massage is will be a bit different from physiological increase in blood pressure, all though the end result is the same:
1. Carotid sinus massage: increase pressure on carotid artery --> increase stretch --> increase afferent CN IX firing --> signal thru nucleus tractus solitarus in medulla--> increase parasympathetic outflow to heart via CN X firing---> decrease heart rate

2. Physiologic increase in blood pressure: both carotid and aortic baroreceptors involved- they both send signals to the medulla with the effect as explained above.

Attached is an image from Costanzo physiology that schematizes it. I think this is similar to what everyone else said, but just trying to clarify a bit. Hope that helps!
Attached Thumbnails
The role of vagus & glossopharyngeal nerves in Carotid Massage!-screen-shot-2011-06-22-10.30.06-pm.png  

Last edited by heights; 06-22-2011 at 09:38 PM.
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Old 06-27-2011
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so according to costanzo firing rate of vagus should be increased too with carotid massage to slow down h/r....
but what i got in above figure is opposite to it..
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