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Feature | SYMPATHETIC | PARASYMPATHETIC |
Spinal Chord Origin | Thoracolumbar: T5-T12, L1-L2 | Craniosacral: C10 (Vagus Nerve), S2-S4. |
Effects | Widespread | low precision Specific, discrete, local, acute. |
Location of cell bodies | Along the spinal chord, at the sympathetic chain ganglia. | Adjacent to or in the target organ. |
Pre Ganglionic Fibers | Short | Long |
Post-Ganglionic | Long | Short |
The Vagus Nerve: Foregut and Midgut innervation
- In the thorax, the right vagus runs posterior to the esophagus, and the left vagus runs anterior to it.
- Around the esophageal hiatus (T10), the two vagus nerves mix, and then they separate again, to form the right and left vagal trunks.
- Left (Anterior) Vagal Trunk: Gives off Hepatic Branch and Principle Anterior Gastric Branch.
- Right (Posterior) Trunk: Forms the Celiac Plexus ------> Superior Mesenteric Plexus.
- These nerves are perivascular -- they follow the course of the arteries.
Pelvic Splanchnic Nerves: Hindgut innervation
- The Pelvic Splanchnic Nerves are parasympathetic Sacral spinal nerves S2-S4.
- They form Pelvic Plexuses ------> Inferior Hypogastric Plexus ------> Pelvic viscera, and separately, the hindgut.
- These nerves are Non-Perivascular. They do not follow the arteries, but instead crisscross the arteries. The nerves are still located in mesentery.
- The lower anus (below pectinate line) is innervated by somatic nerves -- the pudendal nerve -- not parasympathetic pelvic splanchnic.
- Greater Thoracic Splanchnics: T6-T9, Sympathetic spinal nerves supplying the foregut and midgut.
- Lesser Thoracic Splanchnic: T10-T11, Sympathetic spinal nerves supplying the hindgut, generally.
- Least Thoracic Splanchnic: T12. It supplies the Renal Plexus.
Category:
Anatomy Notes
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