Preganglionic nerve fibers

Nerve: Preganglionic fibers
Autonomic nervous system innervation, showing the sympathetic and parasympathetic (craniosacral) systems, in red and blue, respectively
Latin	neurofibrae preganglionicae
Gray's	subject #185 758

In the autonomic nervous system, fibers from the CNS to the ganglion are known as preganglionic fibers.

All preganglionic fibers, whether they are in the sympathetic division or in the parasympathetic division, are both cholinergic (that is, these fibers use acetylcholine as their neurotransmitter) and myelinated.

Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord than are the parasympathetic ganglia while parasympathetic preganglionic fibers tend to be longer. Another major difference between the two ANS systems is divergence. Whereas in the parasympathetic division there is roughly a divergence factor of roughly 1:4 in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons.

See also

• Postganglionic fibers
• Nerve fiber

External links

• Diagram at uwaterloo.ca

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