Blood Supply and Venous Drainage of Spinal Cord

The spinal cord is supplied with arterial blood by descending arteries that run the length of the spinal cord, and by radicular arteries that arise at the segmental level. The descending arteries comprise the paired posterior spinal arteries, and the unpaired anterior spinal artery. The posterior spinal arteries arise either from the posterior inferior cerebellar arteries (see p. 43), or from the vertebral arteries. They descend the cord on the dorsal (posterior) surface, medial to the dorsal roots. The posterior spinal arteries are of variable diameter as they descend, and at some points become so fine that they seem to be discontinuous. These arteries supply the dorsal horns and the posterior (dorsal) columns (see p. 2).

The anterior spinal artery is formed by a confluence of the anterior spinal arteries at medullary level. The vessel descends the cord in the midline, and supplies the midline rami to the lower medulla oblongata. It also gives off sulcal branches, which enter the spinal cord via the anterior median fissure. Some of the sulcal branches are given off from the anterior spinal artery alternately to right or left, or the sulcal artery may itself divide to form right and left branches. These sul-cal branches supply the spinal cord central gray matter, the lateral and anterior (ventral) columns, the lateral and ventral horns, and the basal portion of the dorsal (posterior) horn.

The radicular arteries arise from segmental vessels, including the ascending and deep cervical arteries, and the intercostal, lumbar, and sacral arteries. The radicular arteries gain access to the cord via the intervertebral foramina, and then divide into anterior and posterior radicular arteries which run together with the ventral and dorsal nerve roots, respectively. They supply the main arterial input to the thoracic, lumbar, sacral, and coccygeal spi nal segments. In the cervical region, blood is supplied equally by left and right radicular arteries, while in thoracic and lumbar regions of the cord the radicular arteries occur more commonly on the left side.

There may be from two to ten anterior radicular arteries. One anterior radicular artery is larger than the others; this is the artery of the lumbar enlargement, or the artery of Adamkiewicz, which may arise from an intercostal artery or a lumbar artery anywhere from segments T8-L3. This artery commonly runs on the left side of the cord together with lower thoracic or upper lumbar spinal roots. The posterior radicular arteries divide on the dor-solateral surface of the cord and join the paired posterior spinal arteries. Their distribution with respect to left or right of the cord is not as marked as that seen with the anterior radicular arteries.

The distribution of the spinal veins is similar in general to that of the spinal arteries. There are two major longitudinal venous trunks running along the cord in the midline, the anterior and posterior spinal veins. These receive cord venous drainage via the sulcal veins. The pos-terolateral and posteromedial veins drain the dorsal horns and posterior funiculi. Ventral areas of the cord are drained by anteromedian and anterolateral veins. The internal vertebral venous plexus drains into the external vertebral venous plexus and from there into the ascending lumbar, azygos, and hemiazygos veins.

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vein anterior spinal.

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posterior spinal vein posterior spinal artery posterior radicular artery spinal artery posterolateral spinal.

vein posterior spinal vein posterior spinal artery anterior spinal.

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Vertebral Venous Plexuses

-internal vertebral venous plexus

_dorsal root sleeve dorsal root ganglion anterior radicular artery

arteries

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Essentials of Human Physiology

Essentials of Human Physiology

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