White Ramus Communicans

The white ramus communicans (plural: rami communicantes, ramus means branch) is the preganglionic sympathetic outflow nerve tract from the spinal cord.

Each of the thoracic, and the first and second lumbar nerves contribute a white ramus communicans to the adjoining sympathetic ganglion., unlike the gray rami which are located at each spinal level. White rami communicantes contain both myelinated and unmyelinated preganglionic sympathetic fibers, (GVE and GVA). The white ramus appears white because there are more myelinated than unmyelinated fibers unlike the gray rami.