Table 2.

Mean ICR location and 95% confidence interval (CI) of the mean location in the superior-inferior and anterior-posterior directions in asymptomatic subjects. Mean locations and 95% CI values are provided in millimeters (mm) from the center of the inferior vertebral body for each motion segment, with positive values denoting the superior and anterior directions and negative values denoting inferior and posterior directions. Significant SI differences were found between all motion segments (all p <.001 after adjusting for multiple comparisons) except the C3/C4 and C4/C5 levels (p = 1.000). No significant AP differences were found between any motion segments (all p ≥ .075 after adjusting for multiple comparisons).

Motion Segment	Lower 95% CI (mm)	Mean Superior-Inferior ICR Location (mm)	Upper 95% CI (mm)	Lower 95% CI (mm)	Mean Anterior-Posterior ICR Location (mm)	Upper 95% CI (mm)
C2/C3	−1.1	−0.3	0.5	−3.9	−2.8	−1.8
C3/C4	0.7	1.5	2.2	−2.7	−1.8	−0.8
C4/C5	0.9	1.6	2.3	−2.9	−1.9	−0.9
C5/C6	2.5	3.2	3.9	−3.1	−2.0	−1.0
C6/C7	5.1	5.9	6.7	−3.1	−2.0	−1.0