17. 下列哪一條肌肉有兩個肌腹 (A) 外翼肌 (lateral pterygoid muscle) (B) 內翼肌 (medial pterygoid muscle) (C) 肩胛舌骨肌 (omohyoid muscle) (D) 甲狀舌骨肌 (thyrohyoid muscle)