The relative motion between various vertebrae of multi-level cervical ligamentous spinal segments (C2-T2), using Bryant angles, is described. A three-dimensional sonic digitizer was utilized to study the motion in flexion, extension, right lateral bending and right axial rotation. Effects of a number of injuries and stabilization (interspinous wiring and acrylic cement, PMMA) on the motion behavior of C5–C6 (injured) and C4–C5 (superior to injured) levels were investigated. The data were normalized with respect to intact specimens. The injury to capsular ligaments at C5–C6 produced a significant increase in the relative motion at C4–C5. Although the interspinous wiring reduced the motion at C5–C6 the C4–C5 motion was still higher. The application of PMMA made the motion at C4–C5 comparable to the intact specimen.