MATERIAL and METHODS: In thirty-two fresh human cadavers, the distance from the posterior tubercle to the sulcus of vertebral artery (VA), the thickness and length of the third segment of VA (V3), the distance of C1/C2 facet to V3, the length, height and shape of the C2 ganglion to the neighboring structures, the distance from medial border of C1 lateral mass to dura mater, the distance of the transverse process of atlas to mastoid tip, the thickness of C1 posterior arcus were measured.

RESULTS: There were variations of sulcus of VA in 14 of 32 cadavers (43.7%), the right VA was larger in 23 cadavers (71.8%). The ganglion was found over the C1 lateral mass screw entry point in 45 of 64 ganglions (70.31%) and below the screw entry point in 19 of 64 ganglions (29.69%). The distance of the medial border of the C1 lateral mass to dural tube was 3.81±0.55 mm at the right side and 3.91±0.59 mm at the left. The thickness of C1 posterior arch was 3.73±0.75 mm at the right side and 3.75±0.77 mm at the left. The mean distance from the transverse process of C1 to the mastoid tip was 15.82±4.49 mm at the right side and 15.46±4.38 mm at the left.

CONCLUSION: This is the most comprehensive and only fresh cadaver study about this region in the literature. Keywords : Anatomical landmark, Craniovertebral junction, Vertebral artery