High-frequency ultrasonography of the neck (C6–C7 level), with the aim of detecting the longus colli (LC). The long arrow indicates the path of the injection needle.SG, stellate ganglion; SCM, sternocleidomastoid; ASM, anterior scalenus muscle; CA, carotid artery; IJV, internal jugular vein; VV, vertebral vein; VA, vertebral artery.