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At least 19 recordsLinked to original sources

[Applied anatomical study of the lingual nerve].

The lingual nerve and its adjacent structures were observed and measured on 32 adult cadavours. Its length was 69.7 mm and it was divided, bounded by the internal pterygoid muscle, into three segments and the length and diameter of them were respectively measured. According to its relationship with the lingual nerve, the submandibular ganglion can be classified into fusion type (being 46.9%) and free type (being 53.1%), and its superoinferior and transeversal diameters were separately measured to be 2.7 and 2.9 mm. The lingual nerve and its lingual branches were closely related to submandibular duct and there were two intersects. The relation and clinical significance of the third segment of lingual nerve and its neighbor structures were studied.

Adult↗

Modulation of rat chorda tympani nerve activity by lingual nerve stimulation.

1. A subpopulation of lingual nerve (LN) fibers surround and/or terminate in taste buds in fungiform papillae. One possible function of these fibers is to modulate chorda tympani fiber (CT) or taste responses. To test this hypothesis, the rat LN was stimulated electrically at various voltages (to 20 V), and single- and multiunit CT responses to water-0.1 M NaCl cycles were recorded before, during, and after LN stimulation. 2. When a thermally controlled water-0.1 M NaCl stimulus cycle was applied onto the tongue's surface, the surface temperature remained constant, independent of the stimulation voltage. In the absence of a liquid stimulus, the tongue's surface temperature increased approximately 4 degrees C upon LN stimulation for voltages > or = 5 V. This temperature increase, caused by vasodilation by way of the axon reflex flare mechanism, was taken as evidence that LN stimulation induces peptide release. 3. Comparison of CT activity before LN stimulation with the activity either during or after stimulation revealed statistically significant changes in CT activity. During LN stimulation the CT activity decreased. After LN stimulation, the variability in amount of CT activity increased. 4. In rats treated postnatally with subcutaneous injections of capsaicin to reduce or eliminate polymodal nociceptors, LN stimulation did not produce increases in the tongue's surface temperature or changes in CT activity. 5. Changes in CT activity could be detected seconds after LN stimulation, suggesting that the intragemmal and/or perigemmal LN fibers modulate CT activity. 6. The physiological implications of this study suggest that CT responses to salt can be modulated by endogenous compounds (probably peptides), eating foods that activate LN responses (e.g., foods that are very acidic or contain capsaicin) may modulate taste responses, and peri- and intragemmal fibers should be considered an integral part of the taste receptor system.

Animals↗

External neurolysis of the lingual nerve.

The lingual nerve is sometimes injured during the surgical removal of an impacted mandibular third molar. The level of sensory recovery was studied in 10 patients who underwent external neurolysis of the lingual nerve. The mean time from third molar surgery to neurolysis was 13.5 months (range 9-24 months). Seven of the 10 patients showed significant improvement, three patients regaining normal sensation. Three patients showed no improvement. These results show that external neurolysis should be considered for patients with altered sensation in the distribution of the lingual nerve.

Cranial Nerve Injuries↗

Lingual nerve injury.

Lingual nerve injury is a common complication following dental and medical procedures. The clinical presentation of lingual nerve injury, its epidemiology, predisposing factors, and anatomy are explored in an attempt to identify those patients at risk for developing neuropathic pain. Nonsurgical and surgical therapies also are discussed.

Adult↗

Presence of nerve cell bodies in the lingual nerve in the third molar area.

The microanatomy of the lingual nerve in the third molar area was studied. Twenty-two pairs of lingual nerves were dissected from human cadavers. The area of each nerve adjacent to the third molar was identified, cut, serially sectioned, and stained with hematoxylin and eosin. Nerve cell bodies were found within the structure of 40 of the 44 individual nerves (90.91%). There were two patterns of organization of the nerve cell bodies: isolated nerve cell bodies and ganglion-like clusters of nerve cell bodies. Because of the proximity of the submandibular ganglion, it can be inferred that these cell bodies are parasympathetic in function. The presence of nerve cell bodies in the lingual nerve in the third molar region could have possible clinical ramifications.

Aged↗

Nerve fiber analysis for the lingual nerve of the human adult subjects.

The neuro-motor control of the human tongue musculature had not been investigated in detail. This study identified first that the lingual nerve should play the neuro-motor control of some lingual muscles. Six en bloc samples (12 sides), including the tissues from the skull base to the hyoid bone, and three whole tongues were obtained from adult human cadavers. The former samples were used for the study of nerve fiber analysis of the lingual nerve with the aid of binocular stereomicroscope, and the latter samples were used for histological study by serial section method. On nerve fiber analysis of the lingual nerve from the trigeminal ganglion to the tongue musculature, we found that the motor- root of the trigeminal nerve gave off its supply to the lingual nerve and traveled into the lingual nerve, and branched to the superior and the inferior longitudinal muscles. On histological study, it was revealed that in the anterior part of the tongue the superior and the inferior longitudinal muscles surrounded the other lingual musculature and combined with the sub-mucosal connective tissues closely like the cutaneous muscle, for example, the facial muscles. The lingual nerve entered the inner side of the space between the genioglossus and the inferior longitudinal muscles with the lingual artery. These findings suggested that the superior and the inferior longitudinal muscles should be innervated by the motor fibers traveled into the lingual nerve from the motor root of the trigeminal nerve, and do not originate from the myotome originating in occipital somites but branchial muscles.

Adult↗

Electrophysiological responses to non-electrolytes in lingual nerve of rat and in lingual epithelia of dog.

Epithelial and neural mechanisms underlying the trigeminal chemoreception of non-electrolytes were investigated in whole-nerve recordings from lingual nerve and in Ussing-chamber studies of isolated lingual epithelia. The non-electrolytes included menthol, amyl acetate, phenethyl alcohol, toluene, methanol, ethanol, propanol, butanol, hexanol and octanol. They produced different lingual nerve responses: methanol and ethanol only increased ongoing activity; longer-chain alcohols initially increased but then suppressed activity below baseline; phenethyl alcohol and toluene only suppressed activity. Their threshold concentrations for lingual nerve responses, with the exception of menthol, were proportional to the octanol:water partition coefficients of the stimuli. The threshold concentration for menthol was significantly lower than predicted by this coefficient. Calculation of the free energy of transfer from the threshold concentrations for the n-alcohols suggests that they undergo partition into a hydrophobic environment such as is found in lipid bilayers. Lanthanum chloride, which inhibited lingual nerve responses to hydrophilic compounds, presumably by blocking their diffusion across tight junctions, did not inhibit responses to these non-electrolytes. At high concentrations, hexanol acted as an anaesthetic in that the lingual nerve no longer responded to thermal and chemical stimuli whereas ethanol, which only increased lingual nerve activity, did not inhibit those responses. Epithelial transport, as indicated by the short-circuit current (Isc) measured across tongues bathed in symmetrical solutions of Krebs-Henseleit buffer, was reversibly inhibited by ethanol, hexanol, octanol, phenyl ethanol and menthol. The stimulus concentration necessary to inhibit 50% of the Isc decreased with increasing octanol:water partition coefficient.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

Immunohistochemical, electrophysiological, and electron microscopical study of rat fungiform taste buds after regeneration of chorda tympani through the non-gustatory lingual nerve.

The sensory innervation of fungiform papillae on the rat dorsal tongue is derived from branches of two cranial nerves: the lingual branch of the trigeminal nerve which provides somatosensory innervation and the chorda tympani (CT) branch of the facial nerve, which provides innervation to the taste buds. Removal of the CT results in degeneration of the taste buds. Removal of both nerves results in reduction in size of fungiform papillae and an altered pattern of keratinization in its epithelium. Regeneration of nerves to the epithelium restores the pre-operative condition. Thus, in addition to their sensory functions, both the CT and lingual seem to exert trophic effects on the phenotypic expression of epithelial cells in the fungiform papillae. We severed both the CT and lingual nerves in rats and sutured the proximal stump of the CT to the distal stump of the lingual to promote regeneration of the CT along the lingual nerve pathway. At the same time, we prevented the proximal stump of the lingual from regenerating into the tongue. Our purpose was to determine whether and how the innervation pattern of the regenerated taste bud might be different from normal under these experimental conditions. We found that reinnervation by the CT through the lingual nerve occurs, that this restores the anatomical and functional integrity of the fungiform taste buds and papillae, and that some papillae, but not all, were richly innervated with subgemmal, extragemmal, and perigemmal neuron-specific enolase, calcitonin gene-related peptide, substance P, and neurokinin A-positive fibers. Moreover, responses to taste stimuli were recorded electrophysiologically from the CT.

Animals↗

A quantitative morphological study of the recovery of cat lingual nerves after transection or crushing.

The morphological changes were examined proximal and distal to crush and transection injuries of the lingual/chorda tympani nerve. Under general anaesthesia the nerve was transected unilaterally in 6 adult cats and crushed with watchmakers forceps in 6 others. After 12 wk, again under general anaesthesia, the injured and contralateral (control) nerves were removed, fixed and embedded for histological examination. Sections were cut from sites proximal and distal to the injury and from a site equivalent to that of the injury on the control side. Using systematic randomised sampling techniques the number of nonmyelinated axons and the number and size of myelinated axons in each nerve at each location was estimated. In addition, the mean number of nonmyelinated axons in each Schwann cell unit was determined. The only significant difference between control and injured nerves proximal to either injury was a reduction in the number of myelinated axons in the chorda tympani after transection, and an increase in their mean size. This indicates a selective loss of smaller fibres and is consistent with the poor recovery of gustatory and thermosensitive fibres previously reported (Robinson, 1989). Distal to both types of injury there was an increase in the number of fascicles. The mean number of myelinated axons was reduced distal to a crush injury but unchanged distal to transection. The number of nonmyelinated axons distal to a transection injury was 5 times control counts and after a crush injury double. These findings suggest that sprouting persists 12 wk after both injuries but is much greater after transection.

Animals↗

Lingual nerve injury during suspension microlaryngoscopy.

Lingual nerve injury is an uncommon complication of laryngoscopy. We report a case of isolated unilateral lingual nerve injury that occurred during suspension microlaryngoscopy. The injury was transient, with complete return of sensation within 3 months after surgery. Several mechanisms have been proposed to explain the occurrence of lingual nerve injury during laryngoscopy, including direct compression of the nerve caused by the laryngoscope, stretching of the nerve caused by cricoid pressure or instrumentation, and compression of the nerve between the medial and lateral pterygoid caused by manipulation of the mandible. The precise mechanism of injury in this case was not obvious, but stretching of the lingual nerve caused by pressure of the suspended laryngoscope on the tongue or retrolingual region was likely. The transient nature of the injury and the rapid return of the nerve to baseline function in this case are consistent with a neurapraxic injury.

Adult↗

Effects of lingual nerve and chewing cortex stimulation upon activity of the swallowing neurons located in the region of the hypoglossal motor nucleus.

This study focuses on motoneurons and interneurons in the region of the hypoglossal nucleus (XIIth) related to swallowing and chewing. In sheep anesthetized with halothane, we have used extracellular microelectrodes to study the effects of stimulation of the superior laryngeal nerve (SLN), the lingual nerve (LN) and the chewing cortex (CCx) upon activities of the swallowing neurons (SNs). Ipsilateral stimulation (1-5 pulses at 500 Hz) of the peripheral afferents or CCx did not generally induce a short latency activation of the hypoglossal swallowing motoneurons (Group I SNs) since only 4 motoneurons (69 tested) were activated by the SLN, 4 motoneurons (56 tested) by the LN and none by the CCx. In contrast, the same stimulations were more effective with swallowing interneurons (Group II SNs) located in the reticular formation close to the XIIth motor nucleus since 12 neurons (30 tested) were activated with short latencies (9 +/- 1.8 ms; mean latency +/- S.D.) by the SLN, 9 neurons (21 tested) by the LN (latency; 8 +/- 1.8 ms) and 5 neurons (18 tested) by the CCx (latency: 13 +/- 1.7 ms). Seven neurons were activated by two or three modes of stimulation indicating the existence of convergent inputs upon some Group II SNs. During chewing movements induced by a prolonged stimulation (20-40 Hz) of the CCx, 10 Group I SNs (16 tested) versus only one Group II SN (8 tested) were found to fire in association with the jaw opening. Moreover, 3 motoneurons and 4 interneurons inactive during swallowing discharged during chewing movements.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗

Use of Gore-Tex tubing as a conduit for inferior alveolar and lingual nerve repair: experience with 6 cases.

PURPOSE: This report evaluates treatment outcomes associated with the use of Gore-Tex (GT; W.L. Gore & Associates, Flagstaff, AZ) vein graft tubing as a conduit for repair of inferior alveolar nerve (IAN) and lingual nerve (LN) continuity defects. PATIENTS AND METHODS: Six patients (5 female and 1 male) with painful dysesthesia secondary to injuries of the IAN (n = 3) or LN (n = 3) underwent surgical exploration and resection of pathologic tissue. Reconstruction of the resultant continuity defects was performed using 3-mm diameter GT tubing sutured to the epineurium of the proximal and distal nerve trunks. Nerve reconstruction was performed an average of 20 months after injury (range, 4 to 48 months). Patients were tested before and after surgery with the following tests: subjective pain level using an analogue scale, sharp stimulus, touch, cold sensation, directional sense, and 2-point discrimination. RESULTS: Four patients reported no change in subjective pain level, and 2 patients had minimal decrease in pain. Two patients reported some sensation to sharp stimulus, and 1 patient was hypersensitive. Three patients responded to touch, and 3 had no response. Four patients had no response to cold sensation, and 2 had a delayed response. Only 1 patient could detect brushstroke direction. Three patients had no response to 2-point discrimination, and 3 responded at greater than 20 mm. CONCLUSIONS: Use of GT tubing in this group of patients produced poor clinical outcomes and is not recommended for nerve reconstruction of IAN and LN continuity defects.

Adult↗

[Evaluating methods and effects of repairing injured lingual nerves on human].

We evaluated the regenerations of sense and taste on the anterior 2/3 of the tongue following repairing injured lingual nerve. Injured lingual nerves in 14 patients were repaired with anastomosis of the nerve epineurium. On the anterior 2/3 of the ipsilateral tongue, most of the fungiform papillae atrophied and disappeared, the sense and taste degenerated after severe injury to lingual nerve. Following repair of the injured lingual nerve with anastomosis of nerve epineurium, the papillae and their taste pores can regenerated, 50% of the patients recovered their tongue sense and 35.71% of the patients recovered their tongue taste 1 year after the repair. It is objective, accurate and reliable to evaluate the regenerations of sense and taste on the anterior 2/3 of the tongue after repair of injured lingual nerve by sensory test, taste evaluation, quantitative observation of fungiform papillae, and their taste pores.

Adult↗

Chorda tympani and lingual nerve responses to astringent compounds in rodents.

A wide variety of compounds in foods and beverages produce astringent sensations when introduced into the oral cavity. There is controversy, however, whether "astringency," with its associated puckering and drying sensations, is a fundamental taste quality or is a tactile sensation. To address this issue, electrophysiological recordings were made from the gerbil chorda tympani nerve and the rat lingual nerve. The chorda tympani nerve transmits taste information from the anterior 2/3 of the tongue, whereas the lingual nerve transmits tactile, thermal and pain sensations from the anterior 2/3 of the tongue. The astringent compounds tested were: tannic acid, tartaric acid, gallic acid, aluminum ammonium sulfate and aluminum potassium sulfate. Tannic acid, tartaric acid, and gallic acids were tested at concentrations up to 120 mM over a pH range from approximately 2 to 6. The aluminum salts were tested at concentrations up to 160 mM only at low pH's. All compounds rapidly (and at lower concentrations, reversibly) stimulate the chorda tympani nerve in a concentration-dependent manner at all pH's tested. The rapidity and reversibility of the chorda tympani responses suggest that astringent-tasting compounds interact directly with taste cells rather than indirectly by precipitating salivary proteins. At pH 6, tannic acid, tartaric acid, and gallic acid all elicit robust chorda tympani responses, implying that the ionized forms of these compounds produce taste sensations. None of these compounds stimulate lingual nerves over the same concentration and pH ranges used in the chorda tympani experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗