White Rami Communicantes: Myelinated Preganglionic Sympathetic Fibers and Spinal Nerve Distribution

The white communicating rami contain myelinated preganglionic sympathetic nerve fibers. Preganglionic neurons originate from the intermediolateral cell column of the spinal cord and pass through the ventral root to reach the sympathetic trunk through white rami communicantes.

However, not all spinal nerves have white rami communicantes. They are typically present from C8 through L2, but may be absent from C8 or L2.