Anatomical Morphometric Study of the Cervical Uncinate Process and Surrounding Structures

OBJECTIVE: The purpose of this study is to elucidate the anatomic relationships between the uncinate process and surrounding neurovascular structures to prevent possible complications in anterior cervical surgery. METHODS: Twenty-eight formalin-fixed cervical spines were removed from adult cadavers and were studied. The authors investigated the morphometric relationships between the uncinate process, vertebral artery and adjacent nerve roots. RESULTS: The height of the uncinate process was 5.6-7.5 mm and the width was 5.8-8.0 mm. The angle between the posterior tip of the uncinate process and vertebral artery was 32.2-42.4°. The distance from the upper tip of the uncinate process to the vertebral body immediately above was 2.1-3.3 mm, and this distance was narrowest at the fifth cervical vertebrae. The distance from the posterior tip of the uncinate process to the nerve root was 1.3-2.0 mm. The distance from the uncinate process to the vertebral artery was measured at three different points of the uncinate process : upper-posterior tip, lateral wall and the most antero-medial point of the uncinate process, and the distances were 3.6-6.1 mm, 1.7-2.8 mm, and 4.2-5.7 mm, respectively. The distance from the uncinate process tip to the vertebral artery and the angle between the uncinate process tip and vertebral artery were significantly different between the right and left side. CONCLUSION: These data provide guidelines for anterior cervical surgery, and will aid in reducing neurovascular injury during anterior cervical surgery, especially in anterior microforaminotomy.