人体解剖学-椎管与其内容物Vertebral canal and its contents.ppt

* The CNS is supported and protected by bone and membranous coverings is invested by three concentric meningeal coverings: * * Transverse section of spinal cord showing its meningeal coverings The anterior and posterior spinal arteries alone are insufficient to supply the spinal cord below the cervical level, therefore , they receive serial reinforcement by anastomosis with radicular arteries derived from segmental vessels, including the ascending cervical, intercostal and lumbar arteries * * One particularly large radicular artery may arise at any level from T8~L3 Pass through the intervertebral foramen and divide into anterior and posterior branches, running with ventral and dorsal roots, respectively. Typical vertebrae are supplied by segmental arteries. In the thoracic and lumbar regions, each vertebra is encircled on three sides by paired intercostal or lumbar arteries that arise from the aorta. The segmental arteries supply equatorial branches to the vertebral body, and posterior branches supply the vertebral arch structures and the back muscles. Spinal branches enter the vertebral canal through the IV foramina to supply the bones, periosteum, ligaments, and meninges that bound the epidural space and radicular or segmental medullary arteries that supply nervous tissue Vertebral and ascending cervical arteries in the neck . The major segmental arteries of the trunk: Posterior intercostal arteries in the thoracic region . Subcostal and lumbar arteries in the abdomen . Iliolumbar and lateral and medial sacral arteries in the pelvis * * All of these vessels drain via anterior and posterior radicular veins into internal vertebral venous (epidural) which is situated between the dura mater and vertebral periosteum * Except for the zygapophysial joints and external elements of the vertebral arch, the fibroskeletal structures of the vertebral column (and the meninges) are supplied by the (recurrent) meningeal nerves. Although usually omitted from diagrams an