Communicating branches Concept: communicating branches is the nerve between sympathetic trunk and ant. branches of spinal nerves. White communicating branches: myelinated preganglionic fiber looks like white in fresh Gray communicating branches: unmyelinated postganglionic fiber looks like gray in fresh Grey communicating branch White communicating branch 1717 Communicating branches Concept : communicating branches is the nerve between sympathetic trunk and ant.branches of spinal nerves. White communicating branches: myelinated preganglionic fiber looks like white in fresh. Gray communicating branches: unmyelinated postganglionic fiber looks like gray in fresh. Grey communicating branch White communicating branch