Anatomic considerations of the vertebral artery: implications for anterior decompression of the cervical spine.

Anatomic dissection and measurements of the vertebral artery relative to the medial margin of the longus colli and the anterior margin of the vertebral body from C6 to C3 were performed in this study. The average angle of the vertebral artery relative to the midline was 4.3 +/- 2.6 degrees overall. The average distance between the medial margin of the longus colli and medial margin of the vertebral artery gradually decreased from the C6 level (11.5 +/- 1.0 mm) to the C3 level (9.0 +/- 1.3 mm). The average distance between anterior margin of the vertebral body and anterior margin of the vertebral artery gradually increased from the C6 level (7.2 +/- 1.9 mm) to the C3 level (9.6 +/- 2.1 mm). The distance between medial borders of the longus colli muscles gradually decreased from the C6 level (13.8 +/- 2.2 mm) to the C3 level (7.9 +/- 2.2 mm). Relative to the medial margin of the longus colli muscle and the anterior margin of the vertebral body, the vertebral artery is more lateral and anterior at the C6 level but more medial and posterior at C3 level. This knowledge may facilitate effective decompression of the lateral cervical canal and improve the margin of safety of the surgeon.