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Letters and Responses |
In the July 2000 issue of Physical Therapy, Mautes et al, in an article titled "Vascular Events After Spinal Cord Injury: Contribution to Secondary Pathogenesis,"1 described the blood supply to the spinal cord. The authors stated that a segmental spinal artery enters the intervertebral foramen and divides into 3 branches outside the spinal canal at each segmental level of the spinal cord: the anterior and posterior longitudinal spinal canal arteries and the radicular artery.
Furthermore, Mautes et al described the radicular artery continuing along the nerve root and dividing into an anterior radicular artery and a posterior radicular artery. They stated that, after penetrating the dura mater, the anterior and posterior radicular arteries join the 3 major arteries on the surface of the spinal cord to provide the blood supply to those areas. Mautes et al cited references by Crock and Yoshizawa2 and Domisse3 in their description of the extrinsic blood supply to the spinal cord.
Although Mautes and colleagues' description of anterior and posterior arteries coursing along the spinal nerve roots to join the longitudinal arteries on the surface of the spinal cord may be correct for an embryo during the fourth month of life,4 we believe that they have misrepresented these authors' works by implying that this situation applies to humans after that stage. We believe that their description does not reflect currently accepted (or long-held) views and is misleading. As Lazorthes et al stated, "The classical description of a vertical arterial pathway composed of an anterior and two posterior longitudinal spinal arteries reinforced at each level by rami radiculares was corrected by the observations of Adamkeiwicz6 in 1882, Kadyi7 in 1889, and Tanon8 in 1908."5(p253)
Current accounts of the extrinsic blood supply to the spinal cord in standard anatomical references9–13—based both on these early studies and on recent studies14–16 and utilizing a new, more precise, internationally developed and recognized anatomical terminology17 that may now be universally applied—describe more clearly and accurately the vascularization of the spinal cord in humans and other primates and mammals.
The arteries supplying the spinal cord arise from branches of the vertebral, ascending cervical, deep cervical, intercostal, lumbar, and lateral sacral arteries.9–13 The anterior and posterior spinal arteries originate primarily from the vertebral arteries and run longitudinally from the medulla of the brain stem to the medullary cone of the spinal cord. By themselves, the portions of the anterior and posterior spinal arteries arising from the vertebral arteries can supply only the superior portion of the spinal cord. It has been shown, however, that the circulation to much of the rest of the spinal cord depends on segmental medullary and radicular arteries running along the spinal nerve roots.9–13
The anterior and posterior segmental medullary arteries are derived from the spinal branches of the ascending cervical, deep cervical, posterior intercostal, and lumbar arteries. The medullary segmental arteries are located chiefly where the need for a good blood supply to the spinal cord is greatest—the cervical and lumbar enlargements. These arteries enter the vertebral canal through the intervertebral foramina and reinforce the anterior and paired posterior spinal arteries. It is the segmental medullary arteries that primarily provide additional vascularization to the spinal cord.9–13
The dorsal and ventral radicular arteries are also derived from the spinal branches of the ascending cervical, deep cervical, posterior intercostal, and lumbar arteries. These arteries course along most nerve roots (all except those supplied by a segmental medullary artery) and supply blood to the dorsal and ventral roots of the spinal nerves and their coverings. The dorsal and ventral radicular arteries typically do not reach the anterior or posterior spinal arteries.9–13 Most radicular arteries are small and supply only the nerve roots; however, some radicular arteries may supply the superficial parts of the gray matter in the dorsal and ventral horns and spinal cord. Segmental medullary arteries are the larger vessels that, after supplying or dorsal or ventral root, continue on to reach and anastomose with the spinal arteries, thus providing the additional extrinsic blood supply to the spinal cord.9–13 In fact, it is the segmental medullary arteries such as the named great anterior segmental medullary artery (artery of Adamkiewicz6) that reinforce circulation to two thirds of the spinal cord and the lumbosacral enlargement.9
Professor and Chairman
School of Physical Therapy
Belmont University
Adjunct Professor
Department of Cell Biology
Vanderbilt University
Nashville, Tenn
Associate Professor
School of Physical Therapy
Belmont University
Nashville, Tenn
Professor
Department of Cell Biology
Vanderbilt University
Nashville, Tenn
References
Head
Neurosurgical Research Laboratory
Saarland University Medical School
Homburg, Germany
Medical Faculty
Department of Neurosurgery
University of Technology
Aachen, Germany
Postdoctoral Fellow
Department of Anatomy
University of California
San Francisco, Calif
Professor and Vice Chair
Department of Neurological Surgery
University of California
521 Parnassus Ave
Room C224
San Francisco, CA 94143-0520
References
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