1st year med student

[drsadness88]

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I took the nervous system in anatomy class. Everything was okay except the symapthetic part of the autonomic nervous system. I didn't understand the three pathways when the preganglionic fibers enter the symapthetic truck ganglia. Would someone be very kind and explain them to me in such easy way. I really appreciate it .

Thanks in advance.

p.s is there something like a video or flash the explain the process of that if so please give me the link.

 

[bubbachuck]

This is directly from our syllabus:

The preganglionic fibers originating in the thoracolumbar portions of the spinal cord can do several things after entering the sympathetic trunks:

1. Synapse in the corresponding ganglia at that level. The postganglionic fibers would then rejoin the spinal nerve via a gray communicating ramus. Gray communicating rami consist of unmyelinated postganglionic sympathetic fibers.

2. Ascend or descend the trunk and synapse at a different level. This is the source of preganglionic fibers for ganglia above T1 or below L2. Note: White communicating rami are only found from T1 to L2 or L3. Gray rami are found at all levels.

3. Pass through the sympathetic trunk ganglia without synapsing and travel via the thoracic, lumbar, and sacral splanchnic nerves to the prevertebral (collateral) ganglia.

4. Pass through all of the ganglia (paravertebral and prevertebral) and synapse with chromaffin cells of the adrenal medulla (modified sympathetic ganglion cells).

If you look in Netter's 4 ed. shows a pretty good pic on Plate 167.

 

[Erina]

This is directly from our syllabus:

The preganglionic fibers originating in the thoracolumbar portions of the spinal cord can do several things after entering the sympathetic trunks:

1. Synapse in the corresponding ganglia at that level. The postganglionic fibers would then rejoin the spinal nerve via a gray communicating ramus. Gray communicating rami consist of unmyelinated postganglionic sympathetic fibers.

2. Ascend or descend the trunk and synapse at a different level. This is the source of preganglionic fibers for ganglia above T1 or below L2. Note: White communicating rami are only found from T1 to L2 or L3. Gray rami are found at all levels.

3. Pass through the sympathetic trunk ganglia without synapsing and travel via the thoracic, lumbar, and sacral splanchnic nerves to the prevertebral (collateral) ganglia.

4. Pass through all of the ganglia (paravertebral and prevertebral) and synapse with chromaffin cells of the adrenal medulla (modified sympathetic ganglion cells).

If you look in Netter's 4 ed. shows a pretty good pic on Plate 167.

haha i just read this and thought, wow that sounds really familiar.

then i remembered you go to pitt.