To understand trigeminal neuralgia, we must first start by understanding the trigeminal nerve. The trigeminal nerve is the fifth pair of cerebral nerves, the thickest pair of cerebral nerves in the skull (the left and right branches are called a pair), and is a mixed nerve (a nerve that manages both motor and sensory functions). The motor roots of the trigeminal nerve innervate the movement of the temporalis and masticatory muscles; the sensory roots of the trigeminal nerve manage the sensation of pain, temperature and touch in the face. The sensory roots are thicker than the motor roots and are divided into three branches within the trigeminal nerve hemimelia. The peripheral protrusions of neurons in the anterior medial part of the trigeminal nerve hemimelia form the first branch, the ophthalmic branch; the middle part forms the second branch, the maxillary nerve; the posterior lateral part forms the third branch, the mandibular nerve. It is located in the frontal area, the arch of the eyebrow, the orbit, the nasal cavity, the paranasal area, the upper lip, the cheek and cheekbones, the lower lip, the mandible, the front of the ear, the external auditory canal and the temporal skin (see the figure below); and the oral mucosa, the palate, the tongue, the upper and lower alveoli and the root of the teeth. ”Trigeminal neuralgia” refers to the pain in the area of distribution of the trigeminal nerve mentioned above. The nature of pain can be described as lightning or electric shock-like, knife-like, burning and needle-like severe pain; the duration of pain often varies from several seconds to several minutes, and the duration of pain in advanced patients is significantly prolonged, which can reach half an hour to several hours; the pattern of pain is sudden onset and sudden stop, and the stopping period is like normal people, and the number of pain episodes varies from several times to dozens, and the skin of upper lip, paranasal, lower lip and jaw and oral mucosa, tongue, upper and lower teeth, etc. There are “trigger points” on the tongue and upper and lower teeth. Touching or pressing these “trigger points” can trigger severe pain attacks, so patients dare not speak loudly, and eating, washing, brushing or breezing can lead to repeated pain attacks. If a patient with similar pain can be relieved by the drug carbamazepine, then the pain can be diagnosed as “trigeminal neuralgia”. In addition, the trigeminal nerve innervates the upper and lower alveoli. One third of trigeminal neuralgia is clinically manifested as severe toothache, and patients often go to dentistry first, where the teeth and gums are normal.