[TA] branches of the following arteries and veins that supply and drain the meninges, the roots of the spinal nerves, and in some cases, the spinal cord: 1) vertebral, 2) ascending cervical, 3) dorsal branch of posterior intercostal I-XI, 4) dorsal branch of subcostal, 5) dorsal branch of lumbar arteries, 6) lumbar branch of iliolumbar, 7) lateral sacral; all spinal arteries give rise to arteries supplying dorsal and ventral roots of spinal nerves; most are exhausted in supplying the roots as radicular arteries, but some (4-9), are large enough to reach and anastomose with the anterior and posterior spinal arteries and are designated instead as segmental medullary arteries.great segmental medullary artery, segmental medullary arteries, under artery SYN: rami spinales (1) [TA], spinal arteries.