The location of the spinal nerve root on plain radiographs of the cervical spine.

Twelve cervical spines from C2 to T1 were harvested from embalmed cadavers to study the location of the nerve root on plain radiographs. After removal of the soft tissue, the spinal nerves just lateral to the transverse processes were exposed and injected with lead oxide. Plain radiographs including anteroposterior (AP) and left and right oblique views were taken. Angular and linear measurements were performed directly on the radiographs. Results showed that the average frontal angle of the nerve root for all levels was 155 degrees on the AP view, 108 degrees on the foraminal side of the oblique view, and 153 degrees on the opposite side of the oblique view. The nerve root height for all levels averaged 4.7 +/- 0.5 mm. The interpedicular space height increased consistently from 7.8 +/- 0.7 mm at C3-C4 to 9.0 +/- 1.3 mm at C6-C7 except at C2-C3. The nerve root height with respect to the interpedicular space height was 56.2% at C2-C3, 57.8% at C4-C5, and 53.7% at C6-C7. A knowledge of the location of the cervical nerve root related to plain radiographs may enhance the value of plain radiographs in the diagnosis and treatment of cervical spinal disorders.