ICU Primary PrepCast # Epi 98 - ICU Primary Snippet 41 - Anatomy of Sympathetic Nervous System
May 20, 2025
Dive into the fascinating anatomy of the sympathetic nervous system! Learn about the origins of preganglionic neurons and their pathways through the sympathetic chain. Discover how fibers connect at different levels and the role of splanchnic nerves. Maddy also explains neurotransmitters and receptor types, including unique exceptions like the adrenal medulla. Plus, get insider study tips and diagram recommendations to ace your understanding. It's a compelling journey through critical care anatomy!
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Sympathetic Origins And Ganglia
- The sympathetic chain originates from preganglionic neurons in the lateral horn at T1–L2 and includes prevertebral ganglia for abdominal organs.
- Preganglionic B fibers enter via white rami, can synapse at same/other levels, or pass through to splanchnic nerves and prevertebral ganglia.
Three Pathways Of Preganglionic Fibres
- Preganglionic fibers are short myelinated B fibers that enter the sympathetic chain via white rami communicantes and travel three main paths within the trunk.
- Fibers may synapse at the same level, ascend/descend to other ganglia, or pass through to form splanchnic nerves supplying viscera.
Structure Of The Sympathetic Trunk
- The sympathetic trunk runs bilaterally from skull base to coccyx and consists of cervical, thoracic, lumbar, sacral (and coccygeal) ganglia, including a commonly fused stellate ganglion.
- Postganglionic long unmyelinated C fibers originate in trunk or prevertebral ganglia and reach targets via plexi or distinct nerves.
