Quantitative anatomy of cervical spine ligaments. Part II. Middle and lower cervical spine.

The quantitative anatomy of the ligaments of the middle and lower cervical spine was determined from six human cadaveric specimens using stereophotogrammetry. For each of the ligaments--anterior longitudinal, posterior longitudinal, capsular, ligamentum flavum, interspinous, and supraspinous--the origins, lengths, and orientations were defined three-dimensionally. The anterior and posterior longitudinal ligaments were approximately 7.5 mm wide and 12 mm long at levels C3 through T1, whereas only 3.8 mm wide but 23 mm long and 31 mm long at C1-C2, respectively. The capsular ligaments were fairly constant at all levels, oriented posteriorly at approximately 45 degrees to the transverse plane. The ligamentum flavum were relatively constant in width (5 mm), whereas their lengths increased from 5.2 mm at C2-C3 to 8.7 mm at C7-T1. The interspinous ligament was tilted anteriorly 30-40 degrees and was shortest at levels C2-C3 and C3-C4. The supraspinous ligament was more vertically oriented than the interspinous ligament by 15-20 degrees.