Posted by lae2 on August 14, 2013 at 08:56:29:
1. The sympathetic nervous system has preganglionic cell bodies at spinal levels from T1 to S5.
2. The autonomic nervous syetem, by traditional definition, is a two motor neuron efferent system.
3. The sympathetic nervous system has preganglionic cell bodies in the lateral horn (intermediolateral cell column - IMLCC) at spinal levels S2-4.
4. Parasympathetic activity increases intestinal motility and decreases heart rate (bradycardia).
5. In general, the parasympathetic postganglionic fibers are longer than sympathetic postganglionic fibers.
6. The thoracic sympathetic trunk ganglia can be reasonably likened to a 5 legged spider.
7. The rami comumicantes branch from the anterior aspect of a sympathetic trunk ganglion.
8. The splanchnic nerves branch from the anterior aspect of a sympathetic trunk ganglion.
9. The spinal nerves are posterior to the sympathetic trunk.
10. The greater splanchnic nerve carries preganglionic fibers from the IMLCC of spinal levels T5-9.
11. The white ramus of a ramus communican has its cell body in the IMLCC.
12. The grey ramus of a ramus communican has its cell body in a sympathetic trunk gangion.
13. The sympathetic nervous system contributes thermoregulation by modulating vasoconstriction and to coronary arterial perfusion by vasodilation.
14. The passing of intestinal gas in an elevator requires an concerted effort on the part of the parasympathetic nervous system driving intestinal movements and the somatic nervous system providing tone to the external anal sphincter.
15. Thus, although the autonomic nervous system is involuntary, the voluntary nervous system (somatic) has some oversight.