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In addition to the splanchnic nerves we have discussed, it is important to keep in mind that there are gray rami communicantes to ALL spinal nerves. These gray rami communicantes result in autonomic sympathetic fibers being incorporated into essentially all the branches of all the spinal nerves. Therefore, the sympathetic nervous system reaches virtually every part of the body. It is easy to become confused by gray and white rami communicantes. Remember that white rami communicantes carry presynaptic sympathetic fibers from the ventral primary rami to the sympathetic trunk and exist only between spinal cord segments T1 and L2. Gray rami communicantes carry postsynaptic sympathetic fibers from the sympathetic trunk to all spinal nerves. In spinal cord segments T1-L2 the sympathetic trunk is attached to the spinal nerve by two short branches, the white and gray rami communicantes. Above T1 and below L2, the sympathetic trunk is attached to the spinal nerve (actually, its ventral primary ramus) only by gray rami communicantes. There are NO white rami in the neck or below L2. | 
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