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Operative Spinal Cord Anatomy

Last Updated: October 1, 2018

The spinal cord (SC) is a longitudinal neural structure within the spinal canal, which acts mostly as a conduit for information reaching or leaving the periphery of the body. The SC starts at the foramen magnum and extends to the conus medullaris at approximately the level of the first lumbar vertebra.

The SC is 45 cm in length and is shorter than the spinal canal due to the classical growth mismatch between it and the vertebral column during embryonic development. Thus, in order to maintain the established segmental connections, thoracolumbar roots must elongate to reach their intervertebral foramina.

As a consequence, the upper cervical roots reach their exit almost horizontally to the vertebral level; lower cervical and upper thoracic roots course obliquely one to two segments below; and lumbosacral roots travel almost vertically over several segments in the typical arrangement of the cauda equina.

The SC has a cylindrical shape, which is slightly flattened in the anteroposterior axis. It follows the curvature of the vertebral column and shows two characteristic enlargements, namely the cervical and lumbar ones, where motor neurons related to the upper and lower limbs concentrate. The first is observed at the cervical spinal cord level from C4 to T2, whereas the latter has a close correlation to the first three lumbar vertebrae. Finally, the conus medullaris is usually aligned to the first lumbar vertebra and gives rise to more than 50 r...