17. 鎖骨下動脈(subclavian artery )與腋動脈( axillary artery)通常以何構造為分界?(A) 第一肋骨(rib)(B) 大圓肌(teres major muscle )(C) 小圓肌(teres minor muscle )(D) 胸小肌(pectoralis minor muscle )