White Communicating Branch of Spinal Nerve (Thoracic; Left)

Origin

The white communicating branches of the spinal nerves, or white ramus communicans, are short myelin rich axonal fasciculations that branch off from each spinal nerve, from the first thoracic nerve down to and including the second lumbar nerve.

Course

The white communicating branches run a short distance from a spinal nerve anteriorly to the sympathetic trunk.

Branches

There are no named branches.

Supplied Structures & Function

Each white communicating branch carries preganglionic sympathetic fibers that will do one of four things:

—synapse at a sympathetic chain ganglion at the same level;

—ascend the sympathetic trunk and synapse in a chain ganglion at a higher vertebral level;

—descend the sympathetic trunk and synapse in a chain ganglion at a lower vertebral level;

—exit the sympathetic trunk without synapsing (splanchnic nerve).

Postganglionic neurons that synapse with the preganglionic sympathetic neurons of the white rami will target blood vessels, sweat glands, and arrector pili muscles throughout the body wall, head, neck, and limbs, or in the case of splanchnic nerves, visceral organs.