Development of ANS
<span style="text-decoration:underline;">Neural crest derived neurons migrate from developing DRG to:
</span>1. Paravertebral (sympathetic chain)
2. Prevertebral ganglia
3. Medulla of developing adrenals
4. Developing gut (enteric NS)

Sympathetic Preganglionic Neurons
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<span style="text-decoration:underline;"><strong>Lateral horn of spinal cord (T1 - L2/3)</strong></span>
1.  synapse in paravertebral ganglia
<span style="text-decoration:underline;"><strong>IML cell column of spinal cord (T5 - T12)</strong></span>
2.  travel via splanchnic n. to prevertebral ganglia

Cholinergic
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Sympathetic Postganglionic Neurons
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<strong>Paravertebral (sympathetic chain)</strong>
<strong>Prevertebral (collateral ganglia)</strong>
Fibers terminate on effector organs

Adrenergic
(except sweat glands)
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Splanchnic Nerves
<strong>Carry sympathetic preganglionic axons from anterior roots to prevertebral ganglia
</strong><span style="text-decoration:underline;">
Cell bodies of splanchnic nerves come from:
</span>greater splanchnic n. = T5-T9 IML
Lesser splanchnic n. = T10-T11 IML
Least splanchnic n. = T11-T12 IML

Sympathetics in DRG
Somatic neurons
Visceral afferent neurons

Sympathetics in White Communicating Rami
<strong>Myelinated Pregnaglionic axons </strong>from ant. rami

Sympathetics in Gray Communicating Rami
<strong>Unmyelinated Postganglionic axons</strong> from paravertebral (sympathetic) ganglia

Superior cervical ganglia
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<strong>Sympathetic ganglia in the head</strong>
<strong>Postganglionic axons travel along blood vessels to targets in head</strong>

Injury to neurons in this pathway can cause horner's syndrome
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Parasympathetic Preganglionic Neurons
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<strong>Brainstem nuclei</strong>
<strong>Sacral spinal cord 

</strong>Cholinergic
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Parasympathetic Postganglionic Neurons
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<strong>In walls of viscera</strong>

Cholinergic
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Enteric Nervous System
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<strong>Neural crest cells migrate to developing gut wall and form 2 plexuses</strong>
1.  Submucosal (Meissner's plexus)
2.  Myenteric (Auerbach's plexus)

Can work in absense of input from the brain / spinal cord
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Meissner's Plexus (submucosal)
<span style="text-decoration:underline;">Enteric NS plexus </span>
1.  regulates secretion by glandular epithelium
2.  regulates motility of muscularis mucosa
3.  sensory signal of material in lumen

Auerbach's Plexus (myenteric)
<span style="text-decoration:underline;">Enteric NS plexus</span>
1.  regulates peristalsis
2.  regulates sphincters

Peristaltic Reflex
1.  Bolus distorts mucosa
2.  Enterochromaffin cells release seratonin (5-HT)
3.  5-HT stimulates nerve endings in lamina propria
     - these sensory neurons are in submucosal (meissner's plexus)
4.  Sensory neurons activate motor neurons in myenteric (Auerbach's) plexus

Visceral Afferents of ANS
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Pain afferents travel w/ sypmathetics

Stretch afferents travel w/ parasympathetics
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