A rare case of the auriculotemporal and inferior alveolar nerves communication.

This case study describes anatomical variations in the branching pattern of the posterior division of the trigeminal nerve and its clinical implications for dental and craniofacial surgery. The study presents two uncommon variations observed in an elderly male cadaver. A communicating branch connecting one of three roots of the auriculotemporal nerve and inferior alveolar nerve just before entering the mandibular foramen on the right side, and three communicating branches between the IAN and lingual nerve on the left side. The presence of such variations may complicate anesthesia associated with oral surgery procedures.

The complete anatomy of the lingual nerve: A meta-analysis with implications for oral and maxillofacial surgery.

Lingual nerve (LN) injury during surgical procedures in the third molar region warrants a detailed study of its common pathway and important variations. Therefore, the objective of this study was to analyze and compile the multiple anatomical variations of the LN for use in oral and maxillofacial surgery. It is anticipated that the results of the present meta-analysis may help to minimize the possible complications when performing procedures associated with this anatomical entity. Major online databases such as PubMed, Web of Science, Scopus, Embase were used to gather all relevant studies regarding the LN anatomy. The results were established based on a total of 1665 LNs. The pooled prevalence of the LN being located below the lingual/ alveolar crest was found to be 77.87% (95% CI: 0.00%-100.00%). The LN was located above the lingual/ alveolar crest in 8.21% (95% CI: 4.63%-12.89%) of examined nerves. The most common shape of the LN was established to be round with a prevalence of 40.96% (95% CI: 23.96%-59.06%), followed by oval at 37.98% (95% CI: 23.98%-53.02%) and flat at 25.16% (95% CI: 12.85%-39.77%). In conclusion, we believe that this is the most accurate and up-to-date study regarding the anatomy of the LN. The LN was found to be located below the lingual/alveolar crest in 77.87% of the cases. Furthermore, the LN was found to enter the tongue under the submandibular duct in 68.39% of the cases. Knowledge about the anatomy of the LN is crucial for numerous oral and maxillofacial procedures such as during the extraction of the third molar.

The sublingual branch of the lingual nerve: Anatomical study and suggestion for a new terminology.

The lingual nerve carries somatosensory fibers from the anterior two-thirds of tongue. The parasympathetic preganglionic fibers arising from the chorda tympani also travel with the lingual nerve in the infratemporal fossa to synapse in the submandibular ganglion to innervate the sublingual gland. However, only a few studies have investigated the specific nerve that innervates the sublingual gland and surrounding tissue i.e., the so-called sublingual nerve. Therefore, this study aimed to clarify the anatomy and definition of the sublingual nerves. Thirty sides from formalin fixed cadaveric hemiheads underwent microsurgical dissection of the sublingual nerves. The sublingual nerves were found on all sides and categorized into three branches, i.e., branches to the sublingual gland, branches to the mucosa of the floor of the mouth, and gingival branches. Additionally, branches to the sublingual gland were subcategorized into types I and II based on the origin of the sublingual nerve. We suggest that the lingual nerve branches should be categorized into five branches, i.e., branches to the isthmus of the fauces, sublingual nerves, lingual branches, posterior branch to the submandibular ganglion, and branches to the sublingual ganglion.

Surgical anatomy of the lingual nerve for palate surgery: where is located and how to avoid it.

PURPOSE: To describe the anatomic relationship of the lingual nerve with the lateral oropharyngeal structures. METHODS: An anatomic dissection of the lateral oropharyngeal wall was conducted in eight sides from four fresh-frozen cadaveric heads. Small titanium clips were placed along the lingual nerve and the most anterior and medial border of the medial pterygoid muscle. Radiological reconstructions were employed for optimal visualization; the coronal view was preferred to resemble the surgical position. The distance between the lingual nerve and the medial pterygoid muscle at its upper and lower portion was measured radiologically. The trajectory angle of the lingual nerve with respect to the pterygomandibular raphe was obtained from the intersection between the vector generated between the clips connecting the upper and lower portion of the medial pterygoid muscle with the vector generated from the lingual nerve clips. RESULTS: The mean distance from the upper portion of the medial pterygoid muscle and superior lingual nerve clips was 10.16 ± 2.18 mm (mean ± standard deviation), and the lower area of the medial pterygoid muscle to the lingual nerve was separated 5.05 ± 1.49 mm. The trajectory angle of the lingual nerve concerning to the vector that describes the upper portion of the most anterior and medial border of the medial pterygoid muscle with its lower part was 43.73º ± 11.29. CONCLUSIONS: The lingual nerve runs lateral to the lateral oropharyngeal wall, from superiorly-inferiorly and laterally-medially, and it is closer to it at its lower third.

Variant innervation of the mylohyoid muscle by the lingual nerve.

The nerve to mylohyoid muscle supplies the mylohyoid and the anterior belly of the digastric muscles, with terminal sensory branches that might innervate the submental skin and mandibular teeth. The nerve to mylohyoid muscle typically originates from the posterior surface of the inferior alveolar nerve right before entering the mandibular foramen. In rare cases, the nerve to mylohyoid muscle arises from the lingual nerve. The variations of the nerve to mylohyoid muscle might have led to failure of an inferior alveolar nerve blockade. During the routine dissection of a cadaveric head, a rare case was identified where the nerve to mylohyoid muscle had origins from both the inferior alveolar and lingual nerves. This case is reviewed and salient literature reviewed.

Anatomical Relationship Between the Lingual Nerve and Submandibular Duct.

ABSTRACT: The purpose of this study was to investigate the anatomical relationship between the lingual nerve and submandibular duct. This study included 1403 patients with submandibular or sublingual gland diseases who underwent intraoral removal of submandibular gland sialoliths, submandibular glands, or sublingual glands. Of all patients, 33 patients underwent bilateral surgeries. All surgeries were performed a single surgeon, and the anatomical relationship between the lingual nerve and submandibular duct was always identified intraoperatively and recorded in the operation recorded. The anatomical relationship was investigated based on the intraoperative findings. The lingual nerve which crosses above the submandibular duct was detected in 8 of 1436 sides (0.6%). There were 4 in the right sides and 4 in the left sides. The lingual nerve below the submandibular gland was seen in 99.4%. Although the lingual nerve crosses above the submandibular duct with a rarer incidence, surgeons should beware of injuring the lingual nerve during intraoral salivary gland surgery.

Variant Innervation of the Medial Pterygoid Muscle from the Lingual Nerve.

During a routine dissection of the infratemporal fossa and lateral face, a branch of the left lingual nerve was observed entering the medial pterygoid muscle. Normally, the nerve to the medial pterygoid is a direct branch from the mandibular nerve, with no communications with the lingual nerve. There are many reports involving variations of the mandibular nerve; however, few reports describe lingual nerve variations involving the medial pterygoid muscle. Reconstructive surgeries for cosmesis and trauma, tumor excision, and impacted third molar removal may all damage the lingual nerve and might, as seen in the present case, affect the medial pterygoid muscle. Given the presumed rarity of this variation, we discuss the possible embryological origins as well as the surgical conflicts that may arise with this type of variation.

How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve.

PURPOSE: This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury. METHODS: Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5 years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland. RESULTS: On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland. CONCLUSION: We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.

Defining the anatomy of the neonatal lingual frenulum.

The lingual frenulum is recognized as having the potential to limit tongue mobility, which may lead to difficulties with breastfeeding in some infants. There is extensive variation between individuals in the appearance of the lingual frenulum but an ambiguous relationship between frenulum appearance and functional limitation. An increasing number of infants are being diagnosed with ankyloglossia, with growing uncertainty regarding what can be considered "normal" lingual frenulum anatomy. In this study, microdissection of four fresh tissue premature infant cadavers shows that the lingual frenulum is a dynamic, layered structure formed by oral mucosa and the underlying floor of mouth fascia, which is mobilized into a midline fold with tongue elevation and/or retraction. Genioglossus is suspended from the floor of mouth fascia, and in some individuals can be drawn up into the fold of the frenulum. Branches of the lingual nerve are located superficially on the ventral surface of the tongue, immediately beneath the fascia, making them vulnerable to injury during frenotomy procedures. This research challenges the longstanding belief that the lingual frenulum is a midline structure formed by a submucosal "band" or "string" and confirms that the neonatal lingual frenulum structure replicates that recently described in the adult. This article provides an anatomical construct for understanding and describing variability in lingual frenulum morphology and lays the foundation for future research to assess the impact of specific anatomic variants of lingual frenulum morphology on tongue mobility. Clin. Anat. 32:824-835, 2019. © 2019 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Anatomy of the lingual nerve: Application to oral surgery.

The purpose of this research is to obtain morphological information about the traveling route, branching pattern, and distribution within the tongue of the lingual nerve, all of which are important for oral surgical procedures. Using 20 sides from 10 Japanese cadaveric heads, we followed the lingual nerve from its merging point with the chorda tympani to its peripheral terminal in the tongue. We focused on the collateral branches in the area before reaching the tongue and the communication between the lingual and hypoglossal nerves reaching the tongue. The collateral branches of the lingual nerve were distributed in the oral mucosa between the palatoglossal arch and the mandibular molar region. Two to eight collateral branches arose from the main trunk of the nerve, and the configuration of branching was classified into three types. More distally, the lingual nerve started to communicate with the hypoglossal nerve before passing the anterior border of the hyoglossus muscle. Nerve communications were also found in the main body and near the apex of the tongue. A thorough understanding of the collateral branches near the tongue, and the communication with the hypoglossal nerve inside the tongue, will help to prevent functional disorders from local anesthesia and oral surgical procedures associated with the lingual nerve. Clin. Anat. 32:635-641, 2019. © 2019 Wiley Periodicals, Inc.

Nerve to mylohyoid branched from the lingual nerve: previously undescribed case.

The lingual nerve is a branch of the mandibular division of the trigeminal nerve. It descends medial and anterior to the inferior alveolar nerve through the pterygomandibular space, runs by the lingual plate and lingual crest at the lower third molar closely, and supplies sensory fibers to the anterior two-thirds of the tongue. Therefore, injury of this nerve is occasionally induced by wisdom tooth extraction and could lead to paralysis of the tongue. The inferior alveolar nerve gives rise to the nerve to mylohyoid just before entering the mandibular foramen, which supplies the mylohyoid and anterior belly of the digastric muscle. We present an extremely rare anatomical variation where the nerve to mylohyoid arose from the lingual nerve near the submandibular duct during routine oral dissection.

Regional Anesthesia for Dentistry and Orofacial Surgery in Rhesus Macaques (Macaca mulatta).

Regional anesthesia is a commonly used adjunct to orofacial dental and surgical procedures in companion animals and humans. However, appropriate techniques for anesthetizing branches of the mandibular and maxillary nerves have not been described for rhesus monkeys. Skulls of 3 adult rhesus monkeys were examined to identify relevant foramina, establish appropriate landmarks for injection, and estimate injection angles and depth. Cadaver heads of 7 adult rhesus monkeys (4 male, 3 female) were then injected with thiazine dye to demonstrate correct placement of solution to immerse specific branches of the mandibular and maxillary nerves. Different volumes of dye were injected on each side of each head to visualize area of diffusion, and to estimate the minimum volume needed to saturate the area of interest. After injection, the heads were dissected to expose the relevant nerves and skull foramina. We describe techniques for blocking the maxillary nerve as well as its branches: the greater palatine nerve, nasopalatine nerve, and infraorbital nerve. We also describe techniques for blocking branches of the mandibular nerve: inferior alveolar nerve, mental (or incisive) nerve, lingual nerve, and long buccal nerve. Local anesthesia for the mandibular and maxillary nerves can be accomplished in rhesus macaques and is a practical and efficient way to maximize animal welfare during potentially painful orofacial procedures.

Morphological Features of the Branching Pattern of the Hypoglossal Nerve.

The hypoglossal or twelfth cranial nerve is the motor nerve to the extrinsic and intrinsic muscles of the tongue, and the superior root of the ansa cervicalis and the thyrohyoid and geniohyoid branches are delivered through the nerve. This study investigated the muscular branches of the hypoglossal nerve to clarify their spatial relationships with the muscles of the tongue and the neighboring structures. The muscles and the nerve were gross anatomically examined in 42 cadavers. The superior root and the thyrohyoid branch left the nerve near the occipital and lingual arteries, respectively. The extrinsic muscles consisted of some components, and the geniohyoid branch and the lingual branches arose on the hyoglossus. The ascending lingual branches formed a plexus on the anterior part of the hyoglossus and were divided into the proximal and distal groups. They supplied the two parts of the hyoglossus, the three bundles of the styloglossus and the superior and inferior longitudinal muscles and communicated with the lingual nerve. The descending lingual branches supplied the inferior part of the genioglossus, and the terminal branches gave intramuscular twigs to its main part and the transverse and vertical muscles. The findings indicated that the branching pattern of the hypoglossal nerve is characterized by the positional relationships to the components of the extrinsic muscles. The hyoid bone can be an effective marker to identify the branches and affected position if it was used in combination with the morphology of the extrinsic muscles, and the knowledge of their variations is also beneficial. Anat Rec, 302:558-567, 2019. © 2018 Wiley Periodicals, Inc.

The lingual nerve: overview and new insights into anatomical variability based on fine dissection using human cadavers.

This article, for both researchers and clinicians, presents an overview of the lingual nerve and highlights how new insights into human anatomical variability can be gained by integrating fine dissection of cadavers with neuroanatomical approaches, microscopic studies, and morphometric techniques. Textbooks mainly provide descriptions of the typical or common gross anatomical appearance of structures in the human body with little reference to the nature and extent of variation that may be encountered within and between populations. Furthermore, few texts attempt to integrate descriptions of the regional distribution and branching of neural structures with their central connections or their microscopic anatomy. Using the lingual nerve as an example from the head and neck region, we show that there is still an important place for detailed fine dissections of human cadavers when they are also integrated with morphometric techniques applied to data representing observed variation at both macro- and micro-levels. It is essential that health professionals have a sound understanding of the nature and extent of anatomical variation displayed normally by their patients so that they can perform procedures, such as local anaesthesia and surgery, safely and also be able to correctly diagnose pathology when it is present.

Variations of the lingual and inferior alveolar nerves and their anomalous relationship with the maxillary artery

The infratemporal fossa is a compact space with multiple contents. Explicit anatomical knowledge regarding the relationship between these neurovascular structures becomes imperative during any surgical intervention. Literature is abounding with variations in this region. It encompasses communication between branches of the mandibular nerve or entrapment of nerves by bony bridges, or even abnormal course and branching pattern of the arteries. However, there are many other variabilities in these structures that are less reported or unreported. The present study is an effort to report the characteristic variations of the lingual and inferior alveolar nerves and their anomalous relationship with the maxillary artery in the infratemporal fossa. The study was conducted bilaterally on 26 adult cadavers. The variations in the origin and course of the lingual & inferior alveolar nerves were noted. The course of the maxillary artery and its relation to the lingual and inferior alveolar nerves was also recorded. The variations were explained under the following types: a) communication between the lingual and inferior alveolar nerves, b) existence of a pterygospinous ligament/bar overlying/separating the lingual and inferior alveolar nerves, c) abnormal course/ absence of the chorda tympani nerve and an alternate taste pathway, d) multiple roots of the lingual and inferior alveolar nerves and e) the unusual course of the maxillary artery. Knowledge of these variations would aid the head & neck surgeons in minimizing the compression symptoms and also avoiding postoperative complications

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Accessory Submandibular Salivary Gland Forming a "Horseshoe" With the Main Submandibular Salivary Gland: A Unique Variation.

Presence of accessory submandibular salivary gland (ASSG) is an extremely rare variation. Knowledge of its relations could be very useful to oral and maxillofacial surgeons, head and neck surgeons, and radiologists. During dissection classes, an ASSG was noted between the mylohyoid and hyoglossus muscles. The main submandibular salivary gland had superficial and deep parts. The deep part was narrow and measured about 5 cm. The lingual nerve passed between the superficial and deep parts. The accessory submandibular gland was situated below and parallel to the deep part of SSG. It also measured 5 cm. The ASSG had its own duct, which joined the duct of main gland. The ASSG and the deep part of the SSG were united at the lateral border of geniohyoid muscle to give a characteristic "horseshoe" appearance. The ASSG overlapped both lingual and hypoglossal nerves.

Revisiting the relationship between the submandibular duct, lingual nerve and hypoglossal nerve.

BACKGROUND: The aim of the study was to evaluate the relations between submandibular duct, lingual nerve and hypoglossal nerve for making a reassessment of this area in fresh frozen specimens. Also, the distance between the angle of the mandible and the vertical line drawn from the point where submandibular duct crossed lingual nerve to the base of the mandible was measured to determine a new landmark for neck surgeons. MATERIALS AND METHODS: Fourteen fresh frozen head and neck specimens were dissected and evaluated. A marginal mandibular incision was made from the mastoid process to the chin. RESULTS: In 8 cases, lingual nerve was crossing the submandibular duct superiorly; in 5 cases, lingual nerve was crossing the duct infero-medially and in 1 case it was parallel to the duct. In 1 case, lingual nerve subdivided into anterior and posterior branches. In 2 cases, 2 parallel submandibular ducts were found and the lingual nerve was crossing the upper duct from superior. In 1 case, lingual nerve was crossing the duct infero-medially and then it was subdividing into branches superior to mylohyoid. In 12 cases, the course of hypoglossal nerve was classical. In 1 case, hypoglossal nerve crossed the submandibular duct medially and coursed parallel to the tendon of posterior belly of digastric. And in another case, hypoglossal nerve crossed the inferior branch of submandibular duct medially. The other structures in this area were as usual. CONCLUSIONS: The main factor for reducing nerve damage during surgery is the understanding of the anatomy of this area.

Anatomical study of the so-called "retromolar gland": Distinguishing normal anatomy from oral cavity pathology.

The minor salivary glands in the retromolar trigone have rarely been studied. The aim of this study was to better define the anatomy of the minor salivary glands in the retromolar trigone and establish the relationships between these and adjacent structures. The gland in the retromolar trigone was exposed and its relationships to surrounding structures were observed on 20 cadaveric sides. The boundaries of the gland included the superior pharyngeal constrictor muscle, the tendon of the buccinator muscle, and loose connective tissue. The gland was not continuous with the pterygomandibular or parapharyngeal spaces, but loose connective tissue was present between glands in the retromolar trigone and the medial pterygoid muscle. To our knowledge, this is the first study to describe the detailed anatomy of the minor salivary gland in the retromolar trigone. We suggest that the minor salivary gland in the retromolar trigone should be named the "retromolar gland." Clin. Anat. 31:462-465, 2018. © 2018 Wiley Periodicals, Inc.

Anatomic and Histological Study of Lingual Nerve and Its Clinical Implications.

Although the risk of injuring the lingual nerve in the mandibular molar area during dental treatment is high, it can be repaired by nerve grafting. However, from the perspective of clinical dentistry, the pathway and histomorphometric characteristics of this nerve remain to be documented in detail. The purpose of the present study was to morphologically elucidate the pathway of the lingual nerve to clarify its significance in a clinical setting. A histomorphometric analysis was also performed in consideration of nerve grafting. The vertical distance between the occlusal plane and the superior margin of the lingual nerve showed a gradual decrease from the premolar toward the distal molar area. This suggests that the risk of injuring the lingual nerve increases gradually toward the distal area. The average total fascicular area of the lingual nerve was 1.90 mm2, which was larger than that of the sural nerve. It is the first-choice donor nerve for grafting. Therefore, even though the total fascicular area of the donor nerve is a little smaller than that of the recipient nerve, nerve grafting should be successful.

The clinical view for dissection of the lingual nerve with application to minimizing iatrogenic injury.

The importance of the position of the lingual nerve in the oral cavity cannot be understated for dentists and oral surgeons. Therefore, the location of the lingual nerve with various positions of the tongue is important. However, most dental and medical students are taught oral cadaveric anatomy where tissues are fixed. Therefore, the focus of this article is to demonstrate how the lingual nerve moves based on tongue movement in fresh tissues and how this is important for dentists and oral surgeons. Clin. Anat. 30:467-469, 2017. © 2017 Wiley Periodicals, Inc.