Most often, the fibers from the lateral grey column will travel along the sympathetic trunk until they synapse on one of the trunk’s ganglia, which then passes on the information via postganglionic fibers in a gray ramus communicans. 31 pairs of gray rami communicantes exit the sympathetic trunk to join the 31 pairs of spinal nerves and travel to targets such as sweat glands, hair follicles, and blood vessels. Some fibers, such as the ones that innervate the heart, join the spinal nerves directly, without first joining a gray ramus communicans.