commissure           
noun [ C ]  medical specialized uk/ˈkɒm.ɪ.sjʊər/ us/ˈkɑː.mə.ʃʊr/
 合缝处;结合处
a surface where two parts meet, for example the lips
  连合神经束
a band of nerves going from one side of the brain or spinal cord to the other to connect similar structures