Carotid sinus vs aortic arch baroreceptor -- Uworld question

[wonderbread12]

So I got a question about some guy who is messing with his collar and he comes in with really low BP & HR

They had both CN9 and CN10 listed as possible sources for the afferent limb causing the low BP.

The correct answer was marked as CN9 but I am confused as to how they would differentiate between the two since this caused an increase in BP via stretch (both carotid and aortic arch are stimulated by increased BP/stretch)

My thought was that since it is next to the carotid artery they were going for CN9 but then when people say "vagal maneuver" for SVT I thought they were activating the vagus. Is this a misconception and that a vagal massage really activates CN9? Can anyone help clear this up?

Thanks!

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[NeuroLAX]

He basically did a carotid massage on himself. The afferent for the carotid sinus is CN 9, efferent from the solitary nucleus in the medulla is CN 10.

FA 2014 pg 280

 

[J ROD]

Yeah, never put pressure on both carotids........definitely a CN9 effect. He gave the reason above.

 

[arda]

i think no one can touch their aortic arch by mistake.

 

[J ROD]

i think no one can touch their aortic arch by mistake.

Yeah, that one takes a little more effort.

 

[thehundredthone]

My thought was that since it is next to the carotid artery they were going for CN9 but then when people say "vagal maneuver" for SVT I thought they were activating the vagus. Is this a misconception and that a vagal massage really activates CN9? Can anyone help clear this up?

To activate the vagus in the vagal reflex an afferent signal must be received. Like everyone in the thread has already said, the afferent is CN IX.