The sympathetic trunk (T1-L2) travels in a downward direction from the skull, just lateral to the vertebral bodies. It interacts with the spinal nerves or their ventral rami by way of rami communicantes.
The sympathetic trunk is a fundamental part of the sympathetic division of the autonomic nervous system. It allows nerve fibres to travel to spinal nerves that are superior and inferior to the one in which they originated. Also, a number of nerves, such as most of the splanchnic nerves, arise directly from the trunks.