The quantitative anatomy of the cervical nerve root groove and the intervertebral foramen.

STUDY DESIGN

The present study evaluated the cervical nerve groove and intervertebral foramen using dried vertebrae and cadaveric cervical spine.

OBJECTIVES

To measure the cervical nerve groove in eight linear and one angular dimensions and the intervertebral foramen in two linear diameters.

SUMMARY OF BACKGROUND DATA

Several anatomic studies of the cervical spine exist, but very little quantitative data have been reported on the cervical nerve groove.

METHODS

Dried cervical vertebrae, C3-C7, from 41 complete vertebral sets (205 vertebrae) and 14 cadaveric cervical spine were obtained for the present study. Anatomic evaluation focused on the cervical nerve groove for dry specimens and intervertebral foramen for cadaveric specimens. Ten linear and one angular measurements were made bilaterally. The mean, range, and standard deviation were calculated for all of the specimens and for male and female specimens separately.

RESULTS

Differences in dimensions of male and female specimens were not found to be statistically significant. The average lengths of the medial zone and distances from the midline of the vertebral body to the anterior border of the medial zone for male and female specimens consistently increased from C3 to C7. The width of the medial zone was larger in C3 than that of C4, C5, and C6 in male and female specimens. The minimum width for all levels ranged 1-2 mm. The medial zone depths gradually increased from C3 (3.2 mm for male and 2.3 mm for female specimens) to C7 (4.9 mm for male and 4.4 mm for female specimens). The smallest anteroposterior distances from the posterior midpoint of the lateral mass to the posterior border of the nerve groove were found in C7 (6.7 mm for male and 6.1 mm for female specimens). The general trend of the foraminal height and width increased from the cephalad to caudal except at C2-C3.

CONCLUSIONS

These data may enhance understanding of the important bony elements associated with the cervical spinal nerves and roots as they pass through the cervical nerve groove and the intervertebral foramen.