The types of synapses can be divided into four compound groups, which are the fast adapting afferent terminal group(FA), the slow adapting afferent terminal group(SA), spinal tract of trigeminal nerve group(VS) and pontine nuclei(SA-VP).

• 4个复合组:快适应纤维组(FA),慢适应纤维组(SA),三叉神经脊束核组(VS),三叉神经脑桥核组(VP)组。