Posted by Nick Ahn on September 13, 2009 at 16:27:13:
In Reply to: Re: about the vagus nerve posted by Aaron on September 13, 2009 at 12:13:55:
hmm okay. so i think this discussion is leading us to conclude that the vagus nerve is strictly intrinsic (though it is a parasympathetic nerve which means that it could be collateral or intrinsic, which was the main source of my original confusion)and therefore it is all preganglionic, and that once it synapses within an organ the postganglionic neurons are simply ANS neurons and not called vagus anymore. i think i get it. thanks A, Julia and Aaron!
: While I understand the logic here, I don't think I agree with it. I lean towards Julia's thoughts.
: A nerve is simply a conduit and collection of axons. Once the preganglionic neurons of the vagus hit their respective organs (or terminal ganglia) and split up, they are no longer the vagus nerve, they're simply ANS neurons, which then synapse with their respective postganglionic neurons. Therefore, the nerve itself is only preganglionic.
: Also, the first true/false question of the lower limb/thorax test from 2006 has this exact question, and it's false.
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: : Aha! A, you gave me an epiphany. thank you very much. If anyone disagrees, please make a post. thanks!
: : : Hi Nick,
: : : This may be basic...but going off Dr. Zagon's notes on the ANS...
: : : Nerves in the ANS are always a two-neuron system (one preganglionic and one post ganglionic). So, I think the question should read "The vagus nerve contains postganglionic parasympathetic NEURONS (not nerves)". Which, I think, should be true. Regardless of where the synapse occurs (within the organ or collaterally), the postganglionic neuron is still part of the nerve.
: : : Does anyone else agree with this?