Introducing a novel intraoral mandibular nerve block technique for loco-regional analgesia in camels (Camelus dromedarius): a cadaveric study using computed tomography.

The aim of this study was to introduce a novel intraoral technique for performing mandibular nerve blocks in dromedary camels (Camelus dromedarius). In this study, 18 adult camel skulls of varying ages and breeds were examined to determine the position of the mandibular foramen. Using a Vernier caliper, three dimensions in millimeters were measured: (1) the distance between the mandibular foramen (MF) and the caudal edge of the third molar tooth at the occlusal surface level, (2) the distance between the MF and the rostral edge border of the mandible's ramus (RER) at the occlusal surface level, and (3) the distance between the MF and the ventral margin border of the mandible (VM). The technique was evaluated using five intact camel cadaver heads (n = 5), and a total of ten mandibular nerve blocks were described. An 18-gauge 80-mm Tuohy needle was inserted into the mouth commissure and advanced caudally while injecting a saline-methylene blue solution. The accuracy of the injection was confirmed through the infiltration of the contrast dye into the target area using computed tomography (CT) and post procedural dissection. Anatomical study of the mandibular nerve site was performed to aid the blind insertion of the needle. The findings contribute to the development of veterinary anesthesia techniques and provide anatomical considerations for clinicians performing oral surgeries in sedated camels. The results demonstrated the successful implementation of the intraoral technique, highlighting its efficacy and reliability in achieving local anesthesia for oral surgeries involving the lower jaw and teeth in sedated camels. Further research studies are needed to evaluate the long-term efficacy and safety of the technique and to compare it with existing approaches.

Investigation of the variability of the pterygomandibular space from the point of view of the target point of the inferior alveolar nerve block.

INTRODUCTION: A thorough knowledge of the anatomy and variability of the pterygomandibular space (PMS) is essential to the success of local anesthesia. This study is aimed at determining the volume of the PMS depending on the shape of the skull, face and mandible using the computed tomography (CT). MATERIALS AND METHODS: anonymized computed tomograms of 48 adult patients were analyzed, the indicators of the cranial index (CI), facial index (FI) according to Yzard, the high lengthy index of the mandible (HLI), the latitudinal-altitude index of the mandible (LAI), the longitudinal latitude index of the mandible (LLI) were calculated. RESULTS: Differences in the volume of the PMS were found depending on the shape of the skull, face and mandible. When determining the CI, the largest volume of space on the right was observed with brachycrania (2.05 ml), on the left - with mesocrania and brachycrania (2.0 ml each). With regard to the FI, the largest volume of space was obtained with medium face on the right side (2.03 ml) and broad and medium types of faces (2.0 ml each) on the left. When calculating the indicators for the shapes of mandible, the largest volume of space was found in the brachygenic (2.05 ml), leptogenic (1.98 ml) and platigenic (1.97 ml) shapes on the right and leptogenic and platigenic shapes on the left (2.0 ml each). There were statistically significant differences in the volume of the right side of the PMS between different shapes according to the cranial index (F = 5.075; p = 0.0095). The most pronounced difference was present between samples with brachycrania and dolichocrania: 0.35 mm³ (95% CI 0.05-0.65); p = 0.0188. There was a statistically significant correlation with sex for parameters on both the right and left sides. The values of indicators in men exceeded those of measurements obtained from women. CONCLUSION: The data obtained determine the differences in the volume of the PMS in individuals with different shapes of the skull, face and mandible, as well as sex differences. Thus, indicating the need to take into account these features when choosing the required amount of anesthetic in clinical practice. The average volume of the PMS space, according to our data, is 1.8-2.0 ml, which is consistent with the clinical data described in the literature.

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 surgical anatomy of the deep temporal nerve: A cadaveric study.

BACKGROUND: The aims of this study were to investigate the surgical anatomy of the deep temporal nerve (DTN) and find (fixed/static) anatomical landmarks that could be used during surgery to localise the DTN branches. METHODS: Ten hemifaces of Dutch cadavers were dissected at the Department of Anatomy of the Radboudumc. Landmarks and measurements of interest were number of branches of the DTN, distance from the tragus to the DTN, and distance from the cranial and caudal parts of the posterior root of the zygomatic bone until the DTN. RESULTS: In this cadaveric study, 10 hemifaces were dissected (male, n = 6 [60%]; female, n = 4 [40%]) with an equal left/right side division. The number of deep temporal branches varied from 2 (30%) to 3 (70%) per side. The mean distance to the tragus varied from 40 to 53 mm, with a mean distance of 44.3 ± 4.4 mm. The mean distance from the cranial part of the posterior root of the zygomatic bone to the DTN varied from 29 to 35 mm, with a mean distance of 31.3 ± 2.1 mm. The distance from the caudal part of the posterior root of the zygomatic bone to the DTN varied from 8 to 17 mm, with a mean distance of 13.4 ± 3.4 mm. CONCLUSION: This study investigated the surgical anatomy and landmarks used for identification of the DTN and its branches. It suggested using firm landmarks for nerve identification, such as the posterior root of the cranial and/or the caudal zygomatic bone.

Morphological integration in inferior alveolar canal and mandibular shapes.

OBJECTIVE: During embryogenesis of mandible, the initial ossification centre begins at the bifurcation of the inferior alveolar (IA) and the mental nerves. Additionally, in congenital anomalies like craniofacial microsomia (CFM), the IA canal is completely absent on the microsomic side. These observations led us to hypothesise that there may be a morphological integration between these structures - the IA nerve and the mandibular shapes. Therefore, the primary objective of this study was to test for morphological integration between these structures and the secondary objective was to determine if there were shape variations in these structures among skeletal Classes I, II and III subjects. SETTING AND SAMPLE POPULATION: The sample size of the study is 80 full-head cone-beam computed tomography (CBCT) scans (age 16-56 years). METHODS: We retrieved CBCT scans from our archived database using specific inclusion/exclusion criteria. In the de-identified CBCT scans, traditional coordinate landmarks and sliding semi-landmarks were placed on the mandible and the IA canal (proxy for IA nerve). Using geometric morphometric analyses, we tested integration between the IA canal and the mandibular shapes. We used Procrustes ANOVA to test for overall shape variations among the three skeletal classes (Classes I, II and III). RESULTS: The IA canal and posterior/inferior border of mandible showed strong integration (r-PLS = .845, P = .001). Similar strong integration was also observed between the IA canal and the overall shape of the mandible (r-PLS = .866, P = .001). Additionally, there was a statistically significant variation in overall shape between skeletal Class I and Class II (P = .008) and Class II and Class III (P = .001). CONCLUSIONS: The strong integration between two structures suggests that the IA nerve may play a role in establishing mandibular shape early in development. We posit this may be important in driving mandibular defects seen in CFM, which warrants further investigation.

Choosing the optimal mandible position for inferior alveolar nerve block (IANB) using finite element analysis.

BACKGROUND: One of the most popular methods of local anesthesia in dentistry, inferior alveolar nerve block (IANB) involves the blockade of the inferior alveolar nerve (IAN) and lingual nerve (LN) in the pterygomandibular space. Despite the large number of works describing the contents of this space, the spatial displacements of the anatomical structures of this area at different positions of the mandible have not been sufficiently studied. The aim of our study was to study the spatial movements of the IAN and inferior alveolar artery (IAA) at various positions of the mandible using computer simulation and finite element analysis to find the safest way to conduct IANB. MATERIALS AND METHODS: Reverse engineering was used to create a model of the cranial base and the mandible based on computed tomography (CT) data obtained from patient N (male, 24 years old), the arteries of the head and neck were designed from the data of multiphase angiography of patient M (female, 61 years old). Masticatory muscles, sphenomandibular ligament, temporomandibular joint and mandibular nerve were modeled in the SolidWorks software package based on an open database of anatomical structures. The finite element grid was generated in the Solidworks software. In the first series of experiments, the displacement of the mandible was modeled along the vertical axis down by 48 mm (maximum opening of the mouth), in the second series, the jaw was displaced vertically by 48 mm with a simultaneous transversal movement of 10 mm, in the third series, the jaw was displaced along the vertical axis down by 34 mm and transversally by 22 mm. RESULTS: The largest distance between IAN and IAA was noted in the third series of experiments. The distance between the nerve and the vessel was minimal in the first series, with an open mouth without lateral displacements. CONCLUSION: The generated computer model opens new possibilities for studying the dynamic anatomy of the pterygomandibular space. The results of this study can be used for further experimental and clinical trials to find the safest approach to the implementation of IANB, as well as applied in the practice of the educational process.

An evaluation of mandibular canal variations: a systematic review and meta-analysis.

The inferior alveolar nerve and vessels are carried via the mandibular canal, which extends bilaterally from the inferior alveolar foramen to the mental foramen. Bifid and trifid mandibular canals result from abnormal fusions of nerve canals. The purpose of this study was to provide an up-to-date and comprehensive analysis of the prevalence of mandibular canal variations among healthy adults, and to identify any potential ethnic, sex, or laterality predilections. The prevalence of the bifid mandibular canal was 18.87% and that of the trifid canal 1.3%. Unilateral variants were three times commoner than bilateral. Each mandibular half had four canals emanating from separate openings on the lingual surface of the mandibular ramus. Retromolar and forward canals were the predominant subtypes, followed by dental; buccolingual were the least frequent. The mean length and diameter of the bifid mandibular canal were 13.62 mm and 1.63 mm, respectively. The possibility of a bifid mandibular canal is a crucial consideration in dental medicine. Because anatomical variations of the mandibular canal are fairly common, awareness of them is essential for anatomy teachers and for surgeons who operate in the oromaxillofacial region.

Risco de lesão do ramo mandibular do nervo trigêmeo na fratura de mandíbula: um estudo anatômico / Risk of injury to the mandibular branch of the trigemal nerve in jaw fracture: an anatomical study

O nervo mandibular V3 é a terceira divisão do nervo trigêmeo, apresenta fibras motoras e sensitivas, sendo a ramificação mista deste nervo. Seus ramos eferentes são responsáveis pela motricidade dos músculos mastigatórios, inerva os músculos milo-hióideo, ventre anterior do digástrico, tensor do véu palatino e tensor do tímpano. Suas fibras aferentes são responsáveis pela sensibilidade da região inferior da face e cavidade oral, dentes inferiores, parte da língua e propriocepção da cápsula da articulação temporomandibular ATM. O objetivo deste estudo é explanar as possíveis lesões no nervo mandibular, suas ramificações e estruturas adjacentes no caso de fraturas na mandíbula, colaborando com informações detalhadas para posterior estudo de acadêmicos e cirurgiões dentistas. Foi realizada uma pesquisa de campo, exploratória e descritiva, com abordagem quanti-qualitativa, para descrição e análise do trajeto do V3 até a sua chegada no osso mandibular, assim como de estruturas que compõem a topografia adjacente a mesma utilizando uma hemiface intacta de um cadáver do sexo masculino no Laboratório de Anatomia Humana das Faculdades Nova Esperança, na cidade de João Pessoa. Devido à proximidade do nervo mandibular com o processo coronoide, fraturas nesta parte do osso mandíbula, podem ocasionar lesões no V3, além de traumas no osso temporal, e consequentemente de todo o gânglio trigeminal. Além destas, estruturas adjacentes como a glândula parótida, artérias maxilar e facial, ATM, e os nervos alveolar inferior, mentual e lingual, podem ser lesionadas em uma fratura mandibular. As lesões nestes nervos, podem resultar em redução grave da qualidade de vida e dor crônica, gerando desconfortos para o paciente. Diante do exposto fica evidente a importância de conhecer a anatomia topográfica da mandíbula e suas estruturas vasculonervosas, seu trajeto e a localização. Houve dificuldade na discussão devido à escassez da literatura em relação à temática proposta. Dessa forma, é necessário motivar novos estudos sobre a temática a fim de ampliar o conhecimento dos profissionais de saúde e estimular novas técnicas para diagnóstico precoce e melhorar os resultados terapêuticos, impactando positivamente na sobrevida de pacientes com fraturas de mandibulares(AU)

The mandibular nerve V3 is the third division of the trigeminal nerve, has motor and sensory fibers, being the mixed branch of this nerve. Its efferent branches are responsible for the motricity of the masticatory muscles, innervating the mylohyoid muscles, anterior belly of the digastric, soft palate tensor and tympanic tensor. Its afferent fibers are responsible for the sensitivity of the lower face and oral cavity, lower teeth, part of the tongue and proprioception of the capsule of the temporomandibular joint TMJ. The aim of this study is to explain the possible injuries to the mandibular nerve, its ramifications and adjacent structures in the case of mandible fractures, collaborating with detailed information for further study by academics and dentists. A field research, exploratory and descriptive, with a quantitative-qualitative approach, was carried out to describe and analyze the path of the V3 until its arrival in the mandibular bone, as well as structures that make up the topography adjacent to it using na intact hemiface of a male cadaver at the Human Anatomy Laboratory of Faculdades Nova Esperança, in João Pessoa city. Due to the proximity of the mandibular nerve with the coronoid process, fractures in this part of the mandible bone can cause injuries to the V3, in addition to trauma to the temporal bone, and consequently to the entire trigeminal ganglion. In addition to these, adjacent structures such as the parotid gland, maxillary and facial arteries, TMJ, and the inferior alveolar, mental and lingual nerves can be injured in a mandibular fracture. Damage to these nerves can result in severely reduced quality of life and chronic pain, causing discomfort for the patient. Given the above, the importance of knowing the topographic anatomy of the mandible and its vascular-nervous structures, its path and location is evident. There was difficulty in the discussion due to the scarcity of literature regarding the proposed theme. Thus, it is necessary to motivate further studies on the subject in order to expand the knowledge of health professionals and encourage new techniques for early diagnosis and improve therapeutic results, positively impacting the survival of patients with mandibular fractures(AU)

Characterization of the pterygomeningeal artery based on branching pattern and muscular distribution.

PURPOSE: The pterygomeningeal (accessory meningeal) artery arises from the middle meningeal or maxillary artery. Although there is the potential that this artery may be wounded by the surgery for the temporomandibular joint disorder, the current state of anatomical knowledge is insufficient. This study investigated the appearance and the branching pattern of this artery as a means to its characterization. METHODS: The pterygomeningeal artery was dissected in 14 cadavers and its branches and their distributions to the muscles inside the mandible were examined. RESULTS: The maxillary artery passed lateral to the lateral pterygoid muscle. The pterygomeningeal artery arose from the middle meningeal or maxillary artery. It ascended anteriorly and coursed medial or lateral to the mandibular nerve. It passed above the pterygospinous ligament and then descended. The ascending trunk gave some lateral branches to the lateral pterygoid muscle. The branches sometimes passed lateral to the mandibular nerve even if the pterygomeningeal artery coursed medial. The descending trunk was divided into middle and medial branches, which supplied the medial pterygoid muscle and the tensor veli palatini, respectively. The pterygomeningeal artery was sometimes equally bifurcate near the origin, and the counterparts passed lateral and medial to the mandibular nerve. The distributions of the medial and lateral counterparts were equivalent to those of the descending trunk and the lateral branches, respectively. CONCLUSION: The pterygomeningeal artery contains three groups of muscular branches, which sometimes appear in a bifurcate form. Their positions relative to the mandibular nerve and the pterygospinous ligament characterize the artery; this information may help to avoid iatrogenic injury.

Temporomandibular joint innervation: Anatomical study and clinical implications.

BACKGROUND: Temporomandibular disorders and related pain are commonly seen in clinical practice. Due to its recurrent nature, they adversely affect a patient's social life. Current knowledge on the temporomandibular joint (TMJ) innervation is debatable and insufficient to ensure optimal treatment for the underlying pathology. This study aimed to elucidate the pathophysiology of temporomandibular pain by revealing the TMJ innervation topography, its variations, and its relationships with the surrounding anatomical structures. This will aid in creating a guide for temporomandibular, infratemporal, and preauricular interventions. METHODS: A total of 20 cadaver half heads, 10 fresh frozen and 10 embalmed, were used. The TMJ nerves were dissected together with the surrounding anatomical structures. RESULTS: We showed that the TMJ is mainly innervated by the auriculotemporal nerve posteriorly, the masseteric nerve anteriorly, the posterior deep temporal nerve anteromedially, and the TMJ branch originating directly from the mandibular nerve medially, and that there are variations in these innervation pathways. Additionally, we emphasized how these nerves might be affected in certain clinical conditions based on their anatomical relationships and pathophysiological mechanisms. To our knowledge, this is the first study showing the existence of a branch of the mandibular nerve directly innervating the TMJ. CONCLUSION: In light of our findings, elucidating TMJ pain based on the anatomical characteristics of the region will allow precise treatment algorithms and better clinical outcomes in these patients. Based on this study, new clinical studies and interventions can be designed to reduce healthcare costs and alleviate the burden of temporomandibular disorders.

A previously unreported variant of the auriculotemporal nerve.

Venous fenestrations are rare and when present often are not pierced by regional nerves. Herein, we report an unusual case of a fenestrated superficial temporal vein (STV). Anterior to the external ear, where the STV and superficial temporal artery normally travel with the auriculotemporal nerve (ATN), the nerve was found to pierce the STV. The fenestration within the STV was approximately 0.35mm in diameter, and there was no sign of compression of the ATN as it traversed this vessel. Following the site of penetration of the STV by the ATN, the nerve had a normal course into the skin and surrounding fascia. To our knowledge, this is the first report of a fenestrated STV being pierced by the ATN. Such an anatomical variation might be considered by clinicians who treat patients with pathology of this region.

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.

Vestibular landmarks to minimize injury to the mental nerve during transoral endoscopic thyroidectomy-vestibular approach (TOETVA) procedure: an anatomical study / Puntos de referencia vestibulares para minimizar la lesión del nervio mentoniano durante el procemiento de abordaje vestibular de tiroidectomía endoscópica transoral (TOETVA): un estudio anatómico

SUMMARY: The aim of this study is to reveal the morphometry of the mental nerve to describe a safe zone for minimizing mental nerve damage during transoral endoscopic thyroidectomy-vestibular approach (TOETVA). This study was performed on 12 cadavers. Localization of mental foramen according to teeth, distances of buccogingival sulcus-lip (BG-L), mental foramen-midline (MF-Midline), mental foramen - buccogingival sulcus (MF - BG), commissure - branching point (Cm - Br), branching point - vertical projection of branching point on lower lip (Br - LVP), vertical projection of branching point on lower lip - commissure (LVP - Cm), commissure - midline (Cm - midline), angles of mental (AM), angular (AA) and labial branches (AL) and branching patterns were recorded. Type 1 was mostly found as branching pattern in this study (45.8 %). A new branching pattern (type 9) was found on one cadaver. Mental foramen was mostly located at level of second premolar teeth. According to morphometric results of this study; supero- lateral to course of angular branch and infero-medial to course of mental branch of mental nerve on lower lip after exiting the mental foramen were described as safe zones during surgery for preserving mental nerve and its branches.

RESUMEN: El objetivo de este estudio fue revelar la morfometría del nervio mental o mentoniano para describir una zona segura y de esta manera, minimizar el daño de este nervio durante la tiroidectomía endoscópica transoral-abordaje vestibular (TOETVA). Este estudio se realizó en 12 cadáveres. Se realizó la localización del foramen mentoniano según los dientes, distancias surco gingival-labio (BG-L), foramen mentoniano-línea mediana (MF-Midline), foramen mentoniano-surco gingival (MF-BG), comisura-punto de ramificación (Cm-Br), punto de bifurcación - pro- yección vertical del punto de bifurcación en el labio inferior (Br - LVP), proyección vertical del punto de bifurcación en el labio inferior - comisura (LVP - Cm), comisura - línea mediana (Cm - línea mediana), ángulos del mentón (AM). Se registraron ramos angulares (AA) y labiales (AL) y patrones de ramificación. El tipo 1 se encontró principalmente como patrón de ramificación en el 45,8 %. Se describe un nuevo patrón de ramificación (tipo 9) encontrado en un cadáver. El foramen mentoniano se localizaba mayoritariamente a nivel de los segundos premolares. Según los resultados morfométricos, supero-lateral al curso de la rama angular e infero-medial al curso de la rama mentoniana del nervio mentoniano en el labio inferior, después de salir del foramen mentoniano, se describieron las zonas seguras, para la cirugía y preservación del nervio mentoniano y de sus ramos.

Inervación suplementaria de la mandíbula y sus Implicancias clínicas: revisión narrativa / Supplemental innervation of the mandible and it´s clinical implications: narrative review

RESUMEN: En condiciones normales, la mandíbula y sus estructuras anatómicas (dientes, musculatura, piel), son inervadas por los ramos de la tercera división del nervio trigémino (nervio mandibular), sin embargo, existen reportes que evidencian inervación suplementaria de los dientes inferiores y la zona del ángulo mandibular. Lo último podría ser responsable del fracaso del bloqueo nervioso con anestesia local. El objetivo principal de esta investigación fue revisar artículos que describen la participación de otros nervios como el milohioideo y los ramos superficiales del plexo cervical, los cuales pueden ingresar a la mandíbula a través de forámenes ubicados a lo largo de su arquitectura. Para esto, se realizó una revisión narrativa de la literatura científica, en inglés y español, desde el año 1971 hasta el año 2019, utilizando las plataformas digitales PubMed, EBSCO, Cochrane library, Scielo y Google Scholar, literatura gris y además de una búsqueda manual. Acorde a los resultados de la revisión, se confirma la existencia de fracasos de técnicas anestésicas mandibulares debido a la inervación accesoria de la mandíbula y de los dientes inferiores, donde los tres principales nervios revisados tienen incidencia en este postulado. Finalmente se plantea un orden de ejecución para realizar la infiltración de anestésico local en la mandíbula para lograr un bloqueo exitoso durante los procedimientos odontológicos que la requieran.

SUMMARY: Under normal conditions, the mandible and its anatomical structures (teeth, muscles, skin) are innervated by the branches of the third division of the trigeminal nerve (mandibular nerve), however, there are reports that show supplementary innervation of the lower teeth and the mandibular angle area. The latter could be responsible for the failure of the nerve block under local anesthesia. The main objective of this research; is to review articles that describe the participation of other nerves such as the mylohyoid nerve, and the superficial branches of the cervical plexus, which can enter the mandible through foramina located along its architecture. For this, a narrative review of the scientific literature was carried out, in English and Spanish, from 1971 to 2019, using the digital platforms PubMed, EBSCO, Cochrane library, Scielo and Google Scholar, gray literature and in addition to a search Handbook. According to the results of the review, the existence of the failures of the mandibular anesthetic techniques due to the accessory innervation of the mandible and the lower teeth is confirmed, where the three main nerves reviewed have an impact on this postulate. In conclusion, an order of execution is proposed to perform local anesthetic infiltration into the jaw to achieve a successful block during dental procedures that require it.

Determinación de la morfología del canal incisivo mandibular mediante tomografía computarizada de haz cónico (CBCT) en población de Valdivia, Chile / Determination of mandibular incisor canal morphology by cone beam computed tomography (CBCT) in a population of Valdivia, Chile

RESUMEN: El canal incisivo mandibular (MIC) es un canal neural que contiene una de las ramas inferiores del nervio alveolar inferior, llamado nervio incisivo mandibular, que puede resultar dañado durante intervenciones quirúrgicas y causar complicaciones postoperatorias. Estudio descriptivo de corte transversal. Se identificó el MIC en la imagen transversal del canino en 83 hemiarcadas. Se registró edad, sexo, hemiarcada, longitudes desde reborde alveolar vestibular de canino a MIC, cortical lingual y vestibular de canino a MIC, base mandibular de canino a MIC y ubicación del MIC (tercio lingual, medio, vestibular). Medidas se registraron en milímetros. Se aplicó test T-student para muestras independientes para variables de longitud y Chi-cuadrado para ubicación espacial del MIC, en relación con grupo etario y sexo. Se evaluó el MIC en todas las muestras (100 %). El MIC fue encontrado mayormente en el tercio medio mandibular (p <0,05). La media desde el MIC a la cortical lingual es de 5,25 mm ? 1,42 mm (derecho) y 5,24 mm ? 1,18 mm (izquierdo). La media desde el MIC a la cortical vestibular fue de 4,42 mm ? 1,29 mm (derecho) y 4,53 mm ? 1,24mm (izquierdo). La media entre centro del canal y reborde alveolar vestibular fue 18,89 mm ? 2,68mm (derecho) y 18,20 mm ? 3,06 mm (izquierdo), media desde centro del MIC al margen basal fue de 9,77 mm ? 1,93 (derecho) y 10,12 mm ? 1,92 mm (izquierdo). Se encontró mayor distribución del MIC en el tercio medio mandibular. Se identificó el MIC en el 100 % de las muestras a través de CBCT por lo que su uso como examen complementario debe ser considerado al planificar cirugías en el sector anterior mandibular.

SUMMARY: The objective of the study was to determine the morphology of the mandibular incisive canal (MIC) and its location using cone beam computed tomography (CBCT) in the population of Valdivia, Chile. Descriptive cross-sectional study. MIC was identified in the canine cross image in 83 quadrants. Age, gender, quadrants, length from buccal alveolar ridge of canine to MIC, lingual and buccal cortical of canine to MIC, mandibular base of canine to MIC, and location of MIC (lingual, middle and buccal third) were recorded. Measurements were recorded in millimeters. Independent sample Student-T test was performed to determine length variables and Chi-square test was performed to determine spatial location of MIC, in relation to age group and gender. MIC was evaluated in all samples (100 %). MIC was found mainly in the mandibular third quadrant (p < 0.05). The mean from the MIC to the lingual cortex is 5.25 mm ? 1.42 mm (right) and 5.24 mm ? 1.18 mm (left). The mean from the MIC to the buccal cortex was 4.42 ? 1.29 mm (right) and 4.53 mm ? 1.24 mm (left). The mean between the center of the canal and the buccal alveolar ridge was 18.89 mm ? 2.68mm (right) and 18.20 mm ? 3.06 mm (left), the mean from the center of the MIC to the basal edge was 9.77 mm ? 1.93 (right) and 10.12 mm ? 1.92 mm (left). A greater distribution of MIC was found in the mandibular third quadrant. MIC was identified in 100 % of the samples through CBCT, therefore, its use as a complementary examination should be considered when planning surgeries in the anterior mandibular area.

An anatomical and histological study of mental nerve branches to the inferior labial glands.

PURPOSE: In this study, we aimed to reveal the detailed anatomy of mental nerve branches to the inferior labial glands. METHODS: Embalmed cadaveric heads were used in this study and the mental nerve branches to the inferior labial glands were dissected. Branches to the glands were then excised for histological observation. RESULTS: On all sides, the inferior labial glands were innervated by small branches arising from mental nerve branches that innervated the lower lip. No nerve branches to the inferior labial gland crossed the midline. Histological observation found that the tissue to the inferior labial gland were composed primarily of nerve fibers with a small number of surrounding vessels. Histological findings in examined specimens were consistent. CONCLUSION: The inferior labial glands were innervated by small branches of the mental nerve to the lower lip.

Evaluation of the course of the marginal mandibular branch of the facial nerve: a fresh cadaveric study.

The aim of this study was to determine the course of marginal mandibular nerve (MMN) in relation to the inferior border of the mandible from the gonion until its terminal insertion to the depressor anguli oris, relating the position to a palpable anatomical landmark with emphasis on the depth of the nerve in relation to platysma and the deep cervical fascia. Twelve fresh adult cadavers were dissected and the mandibular base was contoured using needles with 5mm gaps, starting from the mandibular angle to the muscular termination point of the nerve bilaterally. The distance between the MMN and the mandibular base and total length of the nerve was measured bilaterally. The highest levels of MMN were measured 6.9mm and 6.5mm above, and the lowest levels were measured 4mm and 3mm below the mandibular base on right and left sides, respectively. The mean (SD) total length of the nerve until the muscular termination point was calculated 33.57 (3.41) mm on the right and 33.51 (4.88) mm on the left side. Previous publications that we had read all fell short of defining the schematic pathway of the nerve, as the described landmarks were of a combination of bone and soft tissue, which are not always clinically reliable. We have overcome this difficulty by standardising the inferior border of the mandible as a point in order to trace the marginal mandibular branch pathway. It originates along the gonion and ends at the second premolar tooth area.

Structural features of the anterior region of the mandible.

The research aims were to find out further intraosseous mandible organization indications and to structure it systematically. MATERIAL AND METHODS: in our research 400 mandibles were used: for the intraosseous examinations in total 300 mandibles of persons aged 20-65 were used. For all corpses cephalic index was measured. Segmentation of the mandibles were made by Jigley saw between medial root of the first molar at one side and central and second incisor of the opposite one. After that segments were stained with Schiff's reagent with following preparation. Dry preparations (n = 100) were used in exploration of mental foramen macroanatomy. RESULTS: mental foramen cavity depth was divided into three types: low, n = 33 (depth 269 ± 081 mm), medium, n = 36 (depth 358 ± 092 mm) and deep, n = 31 (depth 417 ± 036 mm); transverse size of the cavity is 3109 ± 041 mm and longitudinal size is 397 ± 055 mm. According to the mandible anterior intraosseous organization research it is possible to make a mental nerve intraosseous canal types systematization: semi-oval; straight; s-shaped type, formed by two opposite and transient bends. The S-shaped type (49%) is more common in persons with a dolichocephalic skull type, especially (57.55%) in mesocephalic type and semi-oval (66.36%) in brachycephalic type. CONCLUSION: nerve in the eponymous mental foramen, (which we would like to call a cavity), is branched into two large branches: the extraosseous branch, which innervates the soft tissues (such as Rr. mentales, Rr. labiales and Rr. gingivales), and the intraosseous branch, which runs from the mental foramen to the symphysis, from the latter branch to the first premolar, to the canine and to the incisors.

Cadaveric Study of Topographic Anatomy of Temporal and Marginal Mandibular Branches of the Facial Nerve in Relation to Temporomandibular Joint Surgery.

PURPOSE: Detailed anatomy of the facial nerve, including the variations among different ethnic groups, is essential to prevent an iatrogenic injury. The purpose of the study was to document topographic anatomy of temporal and marginal mandibular (MM) branches of the facial nerve in relation to temporomandibular joint (TMJ) surgery. The specific aim was to demonstrate detailed course of temporal and MM nerves, their surgical implications, and to compare the results obtained with the previous studies. METHODS: The investigators implemented a prospective cadaveric study. A dissection was carried out on 52 facial halves. The facial nerve was dissected according to the instructions described in the Cunningham's dissection manual. Anatomic landmarks were selected as determined by Al-Kayat and Bramley, and results obtained were compared with previous published articles. RESULTS: The study sample was composed of 52 facial halves (males, n = 35; females, n = 17). The number of branches of temporal nerve varied in dissected facial halves from 3 (n = 37 [70%]), 2 (n = 14 [26%]), to 1 (n = 1 [2%]). The distance between the lowest concavity of the bony external auditory meatus to the point at which the facial nerve bifurcates (distance B) was considerably less in the study population (1.79 cm) when compared with the reported literature (2.3 cm). There was no significant influence of gender and cephalic index on distances measured. There was 1 branch in 15% of the dissected facial halves (1 in 52) and 2 branches in 85% (44 of 52). The MM nerve was seen coursing below the inferior border of the mandible, and in 44 (85%), the nerve was present above the inferior border of mandible all along the course. CONCLUSIONS: The topographic anatomy of the temporal and MM nerves is the same as reported in the literature. The only considerable difference was found in distance B; hence, surgical procedures involving the distance B require special consideration.

Anatomic landmarks for masseteric nerve identification: Anatomic study for a new reference point.

The masseteric nerve is often used as a donor nerve in the treatment of facial paralysis. Even if several anatomical studies described landmarks for its identification, their main disadvantages are the anatomical variability and the changes due to surgery. Sixteen dissections were performed on cadaveric specimens. The masseteric muscle (MM), the zygomatic arch (ZA), the masseteric nerve (MN) and the zygomatic branch of the facial nerve (ZB) were identified and their relationships were measured. The relationships between MN and ZB resulted to be constant, with MN intersecting ZB at a depth of 0,78 cm in the muscle, 1,6 cm below ZA and 0,8 cm from the posterior border of MM. The measures obtained demonstrated as the main zygomatic branch of the facial nerve can be a suitable landmark for the identification of the masseteric nerve, with no variations due to the surgical procedure or patient characteristics.