Abstract: Objective  To observe the adjacent relationship between V3v and C2N  so as to provide morphological basis for the pathogenesis of cervical spondylotic arteriopathy (CSA) and both occipitocervical  pain combined with vertigo.   Methods   Thirty-three sides of head-neck specimens were selected for this investigation. The anatomical dissecting and stripping methods were used to expose the C2N and V3v and the adjacent structure. The crossing part of C2N and V3v, range and morphology were observed. Results   The anterior branch of C2N run laterally and crossed with V3v posteriorly in all specimen (33/33, 100%). According to the degree of contacts between C2N and V3v, these crossing relations could be divided into as three types: ① Simple contact crossing type: The original cord-shape anterior branch of C2N crossed with V3v laterally, with a total of 6 sides accounting for 18.2% ; ②Indentation crossing type: The segment of anterior branch of C2N which was crossing with V3v was in flat or longitudinal indentation shape, with a total of 7 sides accounting for 21.2%; ③Semi-circular wrapped crossing type: the anterior branch of C2N become flattened and wrapped the V3v in semi-circular way, with a total of 20 sides accounting for 60.6% . The anterior branches of C2N and V3v crossed each other in 16 sides at right angles, accounting for 48.5%. The diameters of V3v approaching to the crossing part and the crossing part were (3.82±0.07) mm and (3.35±0.05) mm, respectively. The width- diameter of the anterior branch of C2N approaching to the crossing part and the crossing part were (2.38±0.05) mm and (3.53±0.09) mm, respectively. The distances between intersection part and central line was (23.25±0.39) mm, the distance from crossing part to the ipsilateral lateral atlantoaxial joint was (6.26±0.2) mm, and the distance to the ipsilateral zygapophysial joint of C2 and C3 was (11.78±0.3) mm.    Conclusions   The anterior branch of the C2N formed three transverse crossing relationships with V3v, the dominant one among them is the semi-circular wrapped crossing type, this closing adjacent relations may lead the anterior branch of C2N to compresse V3v and may reduce the blood supply to the brain, it may be one of the pathogenesis of CSA and/or may be the morphological basis of hypertension with occipitocervical pain.

Key words: The V₃ segment of the vertebral artery; ,  , C₂ nerve; ,  , Occipitocervical pain; ,  , Vertebral artery type of cervical spondylosis; ,  , Dissected specimen by stripping