Dalley, 10th Edition

Chapter 2 ■ Back

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cord, respectively (see “Vasculature of Spinal Cord and Spi nal Nerve Roots” in this chapter). Spinal veins form venous plexuses along the vertebral column, both inside and outside the vertebral canal. These plexuses are the internal vertebral venous plexuses (epi dural venous plexuses) and external vertebral venous plexuses , respectively (Fig. 2.29). These plexuses commu nicate through the intervertebral foramina. Both plexuses are densest anteriorly and posteriorly and relatively sparse laterally. The large, tortuous basivertebral veins form within the vertebral bodies. They emerge from foramina on the surfaces of the vertebral bodies (mostly the posterior aspect) and drain into the anterior external and especially the anterior internal vertebral venous plexuses, which may form large longitudinal sinuses. The intervertebral veins receive veins from the spinal cord and vertebral venous plex uses as they accompany the spinal nerves through the IV foramina to drain into the vertebral veins of the neck and segmental (intercostal, lumbar, and sacral) veins of the trunk (Figs. 2.29A and 2.30). Nerves of Vertebral Column Other than the zygapophysial joints (innervated by articular branches of the medial branches of the posterior rami, as described with these joints), the vertebral column is inner vated by ( recurrent ) meningeal branches of the spinal nerves (Figs. 2.30 and 2.31). These small branches are the only branches to arise from the mixed spinal nerve, arising immediately after it is formed and before its division into anterior and posterior rami or from the anterior ramus im mediately after its formation.

Periosteal and nutrient branches

Radicular or segmental medullary arteries

Posterior branch of posterior intercostal artery

Posterior intercostal artery

Nutrient arteries

Spinal branch of posterior intercostal artery Posterior vertebral canal branch, to vertebral arch, meninges, and spinal cord

Equatorial branches

Periosteal branches

Anterior vertebral canal branch Superior view

Posterior intercostal artery

Abdominal aorta

body (Bogduk, 2012). The larger branches of the spinal branches continue as terminal radicular or segmental med ullary arteries distributed to the posterior and anterior roots of the spinal nerves and their coverings and to the spinal 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 (spinal nerve roots and spinal cord). FIGURE 2.28. Blood supply of vertebrae. Typical vertebrae are supplied by segmental arteries—here posterior intercostal arteries. In the thoracic and lumbar regions, each vertebra is encircled on three sides by paired posterior intercostal or lumbar arteries that arise from the aorta. These segmental arteries supply equatorial branches to the vertebral body,

Anterior internal plexus Internal vertebral (epidural) plexus Posterior internal plexus

Posterior external vertebral venous plexus

Anterior external vertebral venous plexus

Posterior external vertebral venous plexus

Anterior and posterior longitudinal sinuses (veins) of internal vertebral (epidural) plexus

Dorsal vein

Basivertebral veins

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Lumbar vein Ascending lumbar vein (cut end)

Vertebral body Spinous process

Intervertebral (IV) vein

IV disc

Anterior external vertebral venous plexus Basivertebral vein

(A) Superior view, transverse section of vertebral body

(B) Median section

FIGURE 2.29. Venous drainage of vertebral column. A. Pattern of drainage. The venous drainage parallels the arterial supply and enters the external and internal vertebral venous plexuses. There is also anterolateral drainage from the external aspects of the vertebrae into segmental veins. B. Nature of veins. The dense plexus of thin-walled vessels within the vertebral canal, the internal vertebral venous plexuses, consists of valveless anastomoses between anterior and posterior longitudinal venous sinuses.