The lingual nerve is the sensory nerve that provides information in the form of taste to approximately the front two-thirds of the tongue. It also innervates — or provides nerves to — part of the floor of the mouth, allowing for the perception of temperature, pain, and other sensations. The lingual nerve is part of the mandibular nerve, which innervates a significant part of the human jaw area. The mandibular nerve is itself a part of the trigeminal nerve, which provides sensation in the human face. The back of the tongue is innervated by the glossopharyngeal nerve while the larynx and throat process their sensory information through yet another nerve.
The lingual nerve processes different kinds of sensory information. It can, for example, process pain and temperature. It is also involved in the human perception of taste, which is not governed by simple chemical rules except in the case of acids and bases. Acidic substances almost always have a sour taste while alkaline or basic substances nearly always have a bitter taste. Different parts of different nerves are thought to respond to different chemical properties; this process is what is believed to cause the human perception of taste.
The roots of the second and third molars come quite close to the lingual nerve, which can make tooth extractions somewhat dangerous to patients. Damage to the lingual nerve usually results in either pain or loss of sensation, which may be temporary or permanent, in the areas serviced by the nerve. In some cases, the inferior alveolar nerve is injured; injuries to the lingual nerve tend to be notably more serious. In many instances, the professional extracting the tooth or teeth can identify nerve damage and recommend a nerve repair specialist.
Sometimes, damage to the lingual nerve can be irreparable and can result in chronic pain in the tongue. People deal with such situations in a variety of ways; the treatment for chronic pain from damage to the lingual nerve is not much different from the treatment for other chronic pain issues. Hypnotherapy has been shown to be somewhat successful at controlling pain. Various pain medications of various strengths have also been effective, but those who choose this method of treatment may risk addiction. Surgeries to repair or block the damaged nerves have been employed with varying degrees of success as well.