2.以下何者為手部蚓狀肌(lumbricals)的主要作用? (A)掌指關節屈曲&指間關節屈曲(metacarpal flexion & interphaiangeal flexion)(B)掌指關節伸直&指間關節伸直(metacarpal extesion& interphaiangeal extension)(C)掌指關節屈曲&指間關節伸直(metacarpal flexion& interphaiangeal extension) (D)掌指關節伸直&指間關節屈曲(metacarpal extension & interphaiangeal flexion)