The purpose of this study clarified the sensory nerves that innervate the area near the trigger point of the jaw opening reflex. The trigger point is located at the midpoint between the palatoglossal arch and pterygomandibular fold and medial to the retromolar pad. For the morphological investigation of sensory innervation in this area, we exposed the cranial nerves in 52 halves of cadaver head and observed their distribution in soft tissue. In all the observed examples, the branches of the lingual nerve together formed mesh networks and distributed to the mucosa near the palatoglossal arch, retromolar pad, and the lingual gingiva of the last molar. It was suggested that the sensory nerves distributing to the area around the trigger point of jaw opening reflex were the branches of the lingual nerve, namely the branches to isthmus of fauces. We believe that the information herein may be of use to substantial nursing care and dysphagia rehabilitation.