Fig. 1. Illustration of an axial view of the cervical intervertebral foramen and adjacent structures at the level of C6 with a needle inserted parallel to the axis of the foramen along its posterior wall. Note the proximity of adjacent structures: C6 = vertebral body of C6; CA = common carotid artery; IJV = internal jugular vein; sap = superior articular process of C5–C6 zygapophysial joint; ScA = anterior scalene muscle; ScM = middle scalene muscle; VA = vertebral artery.