GROSS ANATOMY

Detailed explanation-1: -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 cholinergic (that is, these fibers use acetylcholine as their neurotransmitter) and they are myelinated.

Detailed explanation-2: -Postganglionic autonomic nerve fibers in the sympathetic and parasympathetic nervous system are unmyelinated as are C-sensory nerve fibers that support temperature sensation. Preganglionic autonomic fibers and sensory fibers involved in cold and pain sensation are small myelinated nerve fibers.

Detailed explanation-3: -The preganglionic sympathetic neurons are myelinated and look white, thus they travel in white rami. These travel with the spinal nerve (ventral rami) to reach the white ramus.

Detailed explanation-4: -Fibers that leave the ganglion (postganglionic fibers) are not myelinated and tend to be collected in the “gray” ramus. Type II rami are gray rami with few myelinated (preganglionic) fibers. Type III rami are mixtures of gray and white fibers. Gray and white rami can also be multiple.

Detailed explanation-5: -The sympathetic nerves-also called the “C fiber” or “small fiber” nerves-arise from little collections of nerve clusters called ganglia. These are located outside of the spinal cord. The ganglia can function entirely independently (automatically) from the rest of the nervous system.