Anatomy & Organs

Nervus lingualis – structure, function & diseases

Lingual nerve

The lingual nerve, or tongue nerve , innervates the front two-thirds of the tongue and includes both sensory and sensitive fibers. It belongs to the mandibular nerve , which is subordinate to the trigeminal nerve . Lesions can result in taste disturbances , difficulty swallowing , and physiological speech disorders.

What is the lingual nerve?

The lingual nerve runs through the area of ​​the lower jaw . It represents a branch from the mandibular nerve ( Nervus mandibularis ), which in turn is a branch of the Nervus trigeminalus. The trigeminal nerve is the fifth cranial nerve; neural information from the entire face area converges in it.

In addition to the mandibular nerve, the trigeminal nerve has two other main branches: the ophthalmic nerve or eye branch and the maxillary nerve or maxillary branch. The lingual nerve innervates the front two-thirds of the tongue and receives sensory (sensory) information from the taste buds as well as non-specific (sensory) signals related to pressure, temperature, touch, and pain sensations.

The latter are more than just strong touch stimuli; the human body has its own pain receptors (nociceptors), which are often free nerve endings. Since the lingual nerve primarily connects the tongue to the nervous system , it is also known as the lingual nerve.

Anatomy & Structure

The end of the lingual nerve is in the tongue under the mucous membrane . From there, the nerve fibers pass under part of the submandibular salivary gland (glandula submandibularis) before continuing between it and one of the tongue muscles (musculus hyoglossus). At this point, the lingual nerve is lateral to the tongue.

As it progresses, it first crosses one of the outer muscles of the tongue (musculus styloglossus) and then the upper pharyngeal cord (musculus constrictor pharyngis superior), which is one of the muscles of the pharynx . The lingual nerve then runs up the face with the rear part of the mandible (ramus mandibulae) on one side and the medial pterygoid muscle on the other side, passing the inner and outer wing muscles (medial pterygoid muscle and lateral pterygoid muscle). , both of which belong to the muscles of mastication. It continues to the skull as the mandibular nerve . Already in the cranial cavity, the trigeminal nerve divides into this and two other branches.

Function & Tasks

The job of the lingual nerve is to transmit nerve signals. Various fibers within the web can be combined into groups. The sensory fibers carry electrical impulses that nerve cells produce in response to a sensory stimulus. In this case it is a question of gustatory or taste stimuli on the tongue.

The sensory fibers of the lingual nerve must be distinguished from this. They carry information related to touch, pain, and temperature. The sensory fibers form the majority within the nerve. A human has around 100,000 chemical receptors on the tongue and throat that are responsible for taste perception. Several of them are grouped together in a taste bud. Saliva helps dissolve water-soluble molecules from food, allowing taste receptors to respond to each substance.

The molecules either act directly on the ion channels or bind to the receptors, which then open ion channels in the cell membrane. In both cases, the result is a depolarization of the sensory cell: an electrical signal is generated. The individual nerve fibers that make up the lingual nerve are grouped into bundles. A layer of connective tissue separates the 1-3 bundles within the nerve. This covering layer, which is rich in collagen , constitutes the perineurium.

In physiology, the inside of a fascicle is called the endoneurium – it contains the actual nerve fibers that carry information from the tongue to the brain in the form of electrical impulses .

Diseases

Damage to the lingual nerve can result in various sensory disorders of the tongue. Such lesions can occur, for example, as a result of surgery on the jaw, which can be part of dental or orthodontic treatment or used to remove cysts , tumors and other tissue.

A typical example is tonsillectomy. Needle punctures, which are necessary for local anaesthetics , can also accidentally hit the lingual nerve: Although muscles, nerves and other structures in the human body basically follow the same course and structure, slight deviations are possible in individual cases. The exact position of the lingual nerve cannot therefore be estimated with absolute certainty in every case.

In the context of treatments and examinations, medicine also describes such damage as iatrogenic. In addition, injuries in the facial area carry the risk of a lesion on the lingual nerve. Irrespective of the exact cause, signal transmission in the nerve can be completely lost or only partially impaired.

Disorders of gustatory perception are summarized in medicine as dysgeusia. Destroyed nerve fibers that no longer transport stimuli may result in a complete loss of taste in the affected area of ​​the tongue (ageusia). In hypogeusia, on the other hand, the sensitivity to gustatory stimuli is only reduced. Numbness and perceptual disturbances in relation to temperature, pressure, pain and touch are also possible.

Because the lingual nerve does not innervate the entire surface of the tongue, but only the two anterior thirds, a lesion of this nerve does not usually result in total loss of taste. Most of the chemical receptors that a person uses to perceive taste stimuli are located in the back third of the tongue.

In addition to taste disorders, various other complaints can manifest themselves as a result of a lesion on the lingual nerve: swallowing disorders and motor difficulties when speaking are also possible.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.