7. Sympathetic NS
• Visceral afferent – unipolar neurons; soma located in either
cranial sensory or dorsal root ganglia
• Visceral efferent – 2 neurons betn CNS & Organ
preganglionic and postganglionic neurons
• Cell body of preganglionic neurons are located in the lateral
grey columns of the spinal cord
• Their axons pass to peripheral ganglia; synapse with
postganglionic neurons
• The postganglionic neurons(30:1) are more in number & their
axons are usually unmyelinated
• Sympathetic trunk ganglia – C-8, T-11, L-4, S-4
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8. Rami communicantes
White rami communicans preganglionic fibres
Grey ,, ,, postganglionic fibre
All Thoracic & L2 have both
Others have only grey rami communicantes
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9. Preganglionic fibres 4 fate
Synapse with soma of corresponding Sympathetic trunk ganglion
Synapse with soma of other Sympathetic trunk ganglion Up or Down
Leave the trunk without synapsing & pass to ganglion in autonomic plexus (collateral br)
Leave the trunk without synapsing to pass to adrenal medulla
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17. THORACIC SYMPATHETIC TRUNK
• Lie post. to costovertebral pleura
• Contains 11 pairs of ganglion lie ant to head of ribs
• Caudally thoracic sympathetic trunk passes dorsal to medial
arcuate ligament to become lumbar sympathetic trunk
• 1st thoracic ganglion is often fused with inf. Cervical ganglion
forming stellate ganglion
• Each ganglion receives a preganglionic white ramus from the
ventral ramus of its nerve
• After relay in the ganglion a postganglionic grey ramus returns to
each thoracic nerve
• Postganglionic sympathetic fibres supply cardiac, pulmonary
plexus, trachea, oesophagus, thoracic aorta
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19. Splanchnic nerves
Greater Splanchnic nerve – formed by branches of
5th to 9th ganglia
Lesser Splanchnic nerve – from 10th & 11th ganglia
Least Splanchnic nerve – from 12th ganglia
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23. Causalgia
(complex regional pain syndrome type II)
• Result of partial injury to a peripheral nerve
• Sympathetic postganglionic neurons coursing
in the injured nerve develop abnormal
connections to nociceptive dorsal root
ganglion neurons
• S/S – spontaneous burning pain,
hypersensitivity of the skin, pain triggered by
loud noises or strong emotions, sweating and
reduced temperature of the limb, mottling of
the skin, and swelling of the extremityD
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