What is the functional anatomy of the spinal cord involved in cervical radiculopathy?

Updated: Oct 08, 2018
  • Author: Gerard A Malanga, MD; Chief Editor: Sherwin SW Ho, MD  more...
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Answer

Seven cervical vertebrae and 8 cervical nerve roots exist. The C1-2 (atlantoaxial) joint forms the upper cervical segment. [1, 3, 11, 12] This joint allows for 50% of all cervical rotation. The occipitoatlantal joint is responsible for 50% of flexion and extension. Below the C2-C3 level, lateral bending of the cervical spine is coupled with rotation in the same direction. This is due to the 45° inclination of the cervical facet joints.

The vertebral bodies of C3-C7 are similar in appearance and function. They articulate via the zygapophyseal or facet joints posteriorly. On the lateral aspect of the vertebral bodies are sharply defined margins, which articulate with the facet above. These articulations are called uncovertebral joints, or the joints of Luschka. These joints can develop osteophytic spurs, which can narrow the intervertebral foramina.

Intervertebral discs are located between the vertebral bodies of C2-C7. The discs are composed of an outer annular fibrosis and an inner nucleus pulposus and serve as force dissipators, transmitting compressive loads throughout a range of motion (ROM). The intervertebral discs are thicker anteriorly and therefore contribute to normal cervical lordosis.

The foramina are largest at C2-C3 and progressively decrease in size to the C6-C7 level. The nerve root occupies 25-33% of the foraminal space. The neural foramen is bordered anteromedially by the uncovertebral joints, posterolaterally by facet joints, superiorly by the pedicle of the vertebra above, and inferiorly by the pedicle of the lower vertebra. Medially, the foramina are formed by the edge of the end plates and the intervertebral discs. The nerve roots exit above their correspondingly numbered vertebral body from C2-C7. C1 exits between the occiput and atlas, and C8 exits below the C7 vertebral body. Degenerative changes of the structures that form the foramina can cause nerve root compression. This compression can occur from osteophyte formation, disc herniation, or a combination of the 2.


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