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Pain on the body surface can accompany disor-ders in the deep tissue or internal organs.However,the anatomical and physiological mechanisms are obscure.Here,we provided direct evidence of axon bifurcation in primary C-nociceptive neurons that innervate both the skin and a visceral organ.Double-labeled dorsal root ganglion(DRG)neurons and Evans blue extravasation were observed in 3 types of chemically-induced visceral inflam-mation(colitis,urocystitis,and acute gastritis)rat models.In the colitis model,mechanical hypersensitivity and spontaneous activity were recorded in vivo from double-labeled C-nociceptive neurons in S1 or L6 DRGs.These neurons showed significantly enhanced responses to both somatic stimulation and colorectal distension.Our findings suggest that the branching of C-nociceptor axons con-tribute to cutaneous hypersensitivity in visceral inflamma-tion.Cutaneous hypersensitivity on certain locations of the body surface might serve as an indicator of pathological conditions in the corresponding visceral organ.