The level at C7 transverse process. AM, anterior scalene muscle; SCM, sternocleidomastoid muscle; C7, the 7th cervical nerve root; TP, transverse process; VA, vertebral artery; ITA, inferior thyroid artery; PF, anterior vertebral fascia; LCM, long neck muscle; ⋆Indicates stellate ganglion block area; ↘Indicates simulated puncture path; IJV, internal jugular vein; CA, carotid artery.