7．李新手指被刀划破，疼痛难忍，但他紧咬牙关不吭声。此过程中神经冲动的传导路径是

①脑                           ②脊髓                       ③手部感受器             ④传出神经

⑤感觉神经                  ⑥腮部肌肉

A．③⑤②①④⑥                                        B．④②①⑤⑥③

C．③⑤④①④⑥                                        D．③④⑤②④