Twelve (12) pairs of foreroots leave the thoracic spinal cord.
The nerve fibers of the root T1 are included in the arm braid.
The nerve fibers of the roots T2 through T12 are part of the rib nerves (nervi intercostales).
The roots T1 through T12 contain preganglionic sympathetic nerve fibers that emanate from the sympathetic spinal cord nucleus.