Anatomy of Alar Ligament Part I: Morphometrics and Variants.

OBJECTIVE: The alar ligaments are among the primary ligamentous structures contributing to craniovertebral stability. The purpose of this study is to clarify the morphology of the alar ligament using fresh cadaveric specimens. METHODS: Twenty-two fresh, frozen cadaveric alar ligaments were used in this study. The occiput, C1, and C2 were removed en bloc from each specimen, and various measurements and observations including variations were documented. RESULTS: The angle formed by both alar ligaments was measured in a neutral position (149 ± 24.19 degrees), as well as during forced flexion (134.18 ± 27.08 degrees) and extension (163.81 ± 24.54 degrees). CONCLUSIONS: The current cadaveric evaluation offers an interesting window into better understanding the anatomy of the alar ligaments