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Anatomy and localization of spinal cord disorders

Andrew Eisen, MD, FRCPC
Section Editor
Michael J Aminoff, MD, DSc
Deputy Editor
Janet L Wilterdink, MD


Because it is the primary pathway of communication between the brain and peripheral nervous system, diseases that affect the spinal cord are clinically eloquent. Many of these disease processes have a predilection for targeting specific areas or tracts within the spinal cord. As a result, knowledge of spinal cord anatomy and recognition of typical common spinal cord syndromes are useful in the evaluation of a patient with a myelopathy and can allow for a more directed diagnostic evaluation.

The anatomy of the spinal cord and its vascular supply and clinical features of common spinal cord syndromes will be reviewed here. Diseases that affect the spinal cord are discussed separately. (See "Disorders affecting the spinal cord".)


There are 31 spinal cord segments, each with a pair of ventral (anterior) and dorsal (posterior) spinal nerve roots, which mediate motor and sensory function, respectively. The ventral and dorsal nerve roots combine on each side to form the spinal nerves as they exit from the vertebral column through the neuroforamina (figure 1).

Longitudinal organization — The spinal cord is divided longitudinally into four regions: the cervical, thoracic, lumbar, and sacral cord. The spinal cord extends from the base of the skull and terminates near the lower margin of the first lumbar vertebral body (L1). Below that level, the spinal canal contains the lumbar, sacral, and coccygeal spinal nerve roots that comprise the cauda equina.

Because the spinal cord is shorter than the vertebral column, vertebral and spinal cord segmental levels are not necessarily the same. The C1 through C8 spinal cord segments lie between the C1 through C7 vertebral levels. The T1 through T12 cord segments lie between T1 through T8. The five lumbar cord segments are situated at the T9 through T11 vertebral levels, and the S1 through S5 segments lie between T12 to L1. The C1 through C7 nerve roots emerge above their respective vertebrae; the C8 nerve root emerges between the C7 and T1 vertebral bodies. The remaining nerve roots emerge below their respective vertebrae (figure 2).

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Literature review current through: Nov 2017. | This topic last updated: Nov 18, 2015.
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