Anatomy ANS Question

[Simi Roy]

Hi Elizabeth,

Regarding question #11 from your handout, can you please explain why there are PREganglion parasympathetics. I walked into your session 10 minutes late b/c I was coming from an AEP session. So I apologize if you went over this already. 

10. While performing heart surgery you accidently cut the cardiopulmonary sympathetic nerve fibers.  Where are the cell bodies of these nerves located?
1. Lateral Horn
2. Ventral Horn
3. Dorsal Root Ganglion
4. Sympathetic chain ganglia
5. Pre-Aortic ganglia

11. From the question above, what kind of nerve fibers are these?
1. Postganglionic sympathetics
2. Preganglionic sympathetics
3. Postganglionic sympathetics and visceral afferents
4. Preganglionic sympathetics and visceral afferents
5. Preganglionic sympathetics, visceral afferents, preganglionic parasympathetics

And to clarify, visceral afferents piggy-back with ALL sympa and parasympathetics, but when it travels with sympa, you get referred pain at the level of the spinal cord that it enters, right? (Parasympa “pain” is unconscious). And visceral afferents are present everywhere except in GRCs.

Thank you,

Simi

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[Hina Budhwani]

Hi Simi,

 

Here is what I think the correct answer is. Of course, wait to confirm with Elizabeth.

 

First of all, she only went over Sympathetic fibers, which are located from T1-L2. So, for the thorax (Heart and lung - T1-T4), the preganglionic symp fibers orginate from lateral horn, just like all other pregang symp fibers (body wall and limb & Abdomen). They leave the lateral horn, travel through ventral root, go out through white rami and enter into the sympathetic chain. Now they do one of the two things. (a) they would either syanapse there (b) or they would travel up the chain to cervical region and synapse there. Post ganlionic fibers leave medially from the sympathetic chain. Hence, the answer to Q10 would be that the cell bodies of cardiopulmonary would be located in "sympathetic chain ganglia"

 

For 11, VAs follow the same route backwards, so they go through the symp chain ganglia, then go through white rami and through dorsal root to the dorsal horn. Hence, for this, the answer would be "postgang symp fibers and VA."

 

hope this helps

-----askan...@googlegroups.com wrote: -----

To: askan...@googlegroups.com
From: Simi Roy
Sent by: askan...@googlegroups.com
Date: 09/04/2011 01:08PM
Subject: [Anatomy DES] Anatomy ANS Question

[Dr.GooJew]

Yes, I think you pretty much got it right Hina. The only thing I want
to clarify is that once the pre-sympathetic nerve is in the
sympathetic chain ganglion, it has 4 options:
Option 1: Synapse in the chain ganglia and distribute the post-
ganglionic fibers thru branches of spinal nerves.
Option 2: Travel up and down the chain and synapse above or below T1
and L2 -> part of our case also (cervical ganglion)
Option 3: Do not synapse at the chain ganglia , but leave the chain to
become spalnchnic nerves (Greater T5-T9, lesser T10-T11 and least T12)
Option 4: Synapse at the ganglia and become splanchnics (regional) ->
This is our case

Since Option 4 and 2 is part of our scenario (sympathetic nerves from
many levels innervate the heart), the synapse to the post-sympathetic
nerves (also called post-ganglionic nerve) happens in the Sympathetic
Chain Ganglia. Remember, while sympathetic nerves exit the spinal cord
between T1-L2, the SCG runs the WHOLE length of the spinal cord (So as
a side note, if they ask you where do you see gray rams communicants -
> C1 to coccyx because post fibers will arise from all spinal cord
segments, but white rami are only seen from T1-L2).

For the second question, ANS is primarily described as an efferent
system. However, SEPARATE afferent (sensory) fibers travel alongside
the efferent nerve fibers, which carry impulses from the target organ
(similar to the somatic system). And yes, as far as i know the sensory
fibers always go up the white ramus and not the gray ramus, but i
don't know why. It's just the way it is. So the answer for 11 is
visceral afferents and post ganglionic sympathetic nerve fibers
(explained why above)

Some additional clarification on that subject is that while
parasympathetics and sympathetics efferents both have visceral sensory
afferents they can be separated as to their function. Generally,
parasympathetic afferents mediate unconscious sensations resulting in
involuntary physiological responses, eg. enhanced peristalsis,
decrease heart rate, etc. Generally, sympathetic afferents mediate
conscious sensations that are usually PAINFUL, eg. heart attack, gas
pains, appendicitis, etc. and are caused by anoxia (result of
decreased blood supply), distension, inflammation, or spasmodic
contraction of muscles.

As for referred pain, for the sake of discussion and because I'm tired
of typing, you guys give everyone an explanation of how referred pain
works. Simi, you had the general essence of it, but I think you or
someone else can give a more complete explanation. (Some things to
think about in the reply: route, give an example (heart), describe
visceral vs somatic pain, is visceral pain sensation represented in
the brain?)

~Raju

On Sep 4, 6:07 pm, Hina Budhwani <hbudh...@sgu.edu> wrote:
> Hi Simi,
>
>  
>
> Here is what I think the correct answer is. Of course, wait to confirm with Elizabeth.
>
>  
>
> First of all, she only went over Sympathetic fibers, which are located from T1-L2. So, for the thorax (Heart and lung - T1-T4), the preganglionic symp fibers orginate from lateral horn, just like all other pregang symp fibers (body wall and limb & Abdomen). They leave the lateral horn, travel through ventral root, go out through white rami and enter into the sympathetic chain. Now they do one of the two things. (a) they would either syanapse there (b) or they would travel up the chain to cervical region and synapse there. Post ganlionic fibers leave medially from the sympathetic chain. Hence, the answer to Q10 would be that the cell bodies of cardiopulmonary would be located in "sympathetic chain ganglia"
>
>  
>
> For 11, VAs follow the same route backwards, so they go through the symp chain ganglia, then go through white rami and through dorsal root to the dorsal horn. Hence, for this, the answer would be "postgang symp fibers and VA."
>
>  
>
> hope this helps
>
> -----askan...@googlegroups.com wrote: -----
>
> To: askan...@googlegroups.com
> From: Simi Roy
> Sent by: askan...@googlegroups.com
> Date: 09/04/2011 01:08PM

> Subject: [Anatomy DES] Anatomy ANS QuestionHi Elizabeth,

>
> Regarding question #11 from your handout, can you please explain why there are PREganglion parasympathetics. I walked into your session 10 minutes late b/c I was coming from an AEP session. So I apologize if you went over this already. 
>

> While performing heart surgery you accidently cut the cardiopulmonary sympathetic nerve fibers.  Where are the cell bodies of these nerves located?Lateral HornVentral HornDorsal Root GanglionSympathetic chain gangliaPre-Aortic gangliaFrom the question above, what kind of nerve fibers are these?Postganglionic sympatheticsPreganglionic sympatheticsPostganglionic sympathetics and visceral afferentsPreganglionic sympathetics and visceral afferentsPreganglionic sympathetics, visceral afferents, preganglionic parasympatheticsAnd to clarify, visceral afferents piggy-back with ALL sympa and parasympathetics, but when it travels with sympa, you get referred pain at the level of the spinal cord that it enters, right? (Parasympa “pain” is unconscious). And visceral afferents are present everywhereexceptin GRCs.

[Elizabeth Hogan]

Raju and Hina did a great job summing it up.  If anyone is still confused about this topic, you can come see me before DES next week to discuss.  I will be there 15min early.

Elizabeth