21 迷走神經(vagus nerve)行經:(A)頸動脈管(carotid canal)離開顱腔(B)鎖骨下動脈(subclavian artery)之前方(C)脊柱(vertebral column)兩側支配消化腺(D)頸動脈鞘(carotid sheath),與交感神經幹(sympathetic trunk)併行