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PURPOSE: Inferior alveolar nerve (IAN) and lingual nerve (LN) blocks are commonly performed using the intraoral landmark techniques. However, these methods have a risk of unanticipated nerve and arterial injury or a higher failure rate. We developed a novel extraoral approach for the IAN and LN blocks, the "inferior alveolar nerve block mandibular angle approach (IANB-MA)," using ultrasound guidance. The mechanism of action of this nerve block was examined anatomically, and its clinical feasibility was reported. METHODS: We performed the IANB-MA on four cadavers using different dye volumes (2, 4, 6 and 8 mL). The ultrasound probe was placed on the lower edge of the mandibula of each cadaver, and the needle was advanced to the mandibular inner surface. Blue acrylic paint solution was injected, and its spread was evaluated by dissection. RESULTS: Our study showed that the medial pterygoid muscle fascia was stained in all cadavers. The dye reached the LN consistently, and the IAN was stained with higher volumes (6 mL and 8 mL). The pterygomandibular space was filled with 6 mL and 8 mL of the dye. The IANB-MA successfully reduced pain in three patients with trigeminal neuralgia, tongue or jaw pain. CONCLUSIONS: The IANB-MA is a novel ultrasound-guided approach to the IAN and the LN. The clinical feasibility and effectiveness of this technique were confirmed in our patients. It may be a good alternative analgesic approach to other conventional approaches.

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OBJECTIVE: The International Union for Cancer Control/American Joint Committee on Cancer (UICC/AJCC) rT staging is not clinically practical for recurrent nasopharyngeal carcinoma (rNPC). The aim of this study was to establish a new rT staging to guide the treatment of rNPC. METHODS: We conducted a retrospective analysis of 175 patients diagnosed with rNPC between January 2012 and December 2020, using ROC curve analysis to evaluate its effectiveness. RESULTS: We analyzed the overall survival (OS) and progression-free survival(PFS) of patients diagnosed with rNPC according to the 8th (UICC/AJCC) rT staging, and found that the overall survival of rT1 and rT2 patients (OS; 29.98% vs. 27.09%, p = 0.8059) and progression-free survival (PFS; 28.48% vs. 26.12%, p = 0.4045) had no significant difference. In rT1 and rT2 patients of this study, overall survival(OS; 30.44% vs. 24.91%, p = 0.0229) and progression-free survival(PFS 29.12% vs. 24.03%, p = 0.0459) had a significant difference. Smoking, family history, and time interval of initial recurrence were independent prognostic factors for OS and PFS. CONCLUSION: The new rT staging of this study has a better predictive value for survival of rNPC patients than the 8th (UICC/AJCC) rT staging.

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Objetivo: Determinar el efecto del anestésico local di-bucaína sobre las principales isoformas de la SERCA (calcio ATPasa de retículo sarco-endoplásmico) pre-sentes en músculo pterigoideo interno. Métodos: Se aislaron por centrifugación diferencial membranas de retículo sarcoplásmico de pterigoideo interno de conejo neozelandés macho (n=5). Se separaron las isoformas SERCA1a, 2a y 2b por cromatografía de afinidad. Se determinó in vitro la actividad enzimá-tica en presencia de diferentes concentraciones de dibucaína (0-90 mM) por el método de Fiske y Subba-row, realizando 5 experimentos por duplicado y en paralelo para cada isoforma. Se calculó la media y ES de la CI50 (mM) del anestésico para cada isofor-ma y éstas se compararon por ANOVA de una vía (p<0,05), y prueba Student-Newman-Keuls de com-paraciones múltiples. Resultados: Dibucaína inhibió la actividad enzimática en función de su concentra-ción en las tres isoformas en estudio. Las CI50 fueron: SERCA1a 20,02 ± 0,64 mM, SERCA2a 15,03 ± 0,52 mM y SERCA2b 16,00 ± 0,51 mM y resultaron signi-ficativamente diferentes (F2,27 = 11,08, p<0,001). La prueba post hoc identificó diferencias significativas entre SERCA1a y 2a, 1a y 2b. El efecto inhibitorio re-sultó significativamente mayor sobre las isoformas 2a y 2b, cuya presencia es sustancialmente mayor en músculos masticadores. Conclusión: La dibucaína inhibe a la SERCA de pterigoideo interno a concen-traciones menores que las usadas en clínica médica (29 mM). Es un anestésico local con potencial efecto miotóxico derivado de la inhibición de la SERCA (AU)

Aim: To test the effect of the local anesthetic dibu-caine on the main isoforms of the SERCA (sarco-endosplasmic reticulum calcium-ATPase) in medial pterygoid muscle. Methods: Sarcoplasmic reticulum membranes from male New Zealand rabbits (n=5) were isolated from medial pterygoid muscle by ul-tracentrifugation. The isoforms SERCA1a, 2a and 2b were separated using high affinity chromatography. In vitro enzymatic activity determinations were per-formed in the presence of different dibucaine con-centrations (0-90 mM) using the colorimetric method described by Fiske & Subbarow. Five assays in dupli-cate and run in parallel were performed for each of the isoforms. Mean and SEM of the IC50 (mM) for the effect of the anesthetic on each isoform were calcu-lated and compared by one-way ANOVA (p<0.05), and Student-Newman-Keuls multiple comparisons test. Results: Dibucaine inhibited the enzymatic activity in a concentration-dependent manner for the three studied isoforms. The IC50 values were: SERCA1a 20.02 ± 0.64 mM, SERCA2a 15.03 ± 0.52 mM and SER-CA2b 16.00 ± 0.51 mM. The values were significantly different (F2.27 = 11.08, p<0.001). The post hoc test revealed significant differences between SERCA1a and 2a, 1a and 2b. The inhibitory effect was signifi-cantly higher on 2a and 2b isoforms, whose presence is substantially higher in masticatory muscles. Con-clusion: Dibucaine inhibits SERCA in medial pterygoid muscle at concentrations lower than those used in clinical medicine (29 mM). It is a potentially myotoxic local anesthetic whose toxic effect may derive from SERCA inhibition (AU)

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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.

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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.

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BACKGROUND: Little is known regarding the functional properties of single motor units (SMUs) in the medial pterygoid muscle (MPt) during jaw movements. OBJECTIVES: The aims are (a) to report the thresholds of onset of MPt SMUs during 4 goal-directed jaw movement tasks, and (b) to determine whether the threshold of onset of SMU activation varies with the velocity of jaw movement and the location within the muscle. METHODS: Intra-muscular electrodes were inserted in the right MPt of 18 participants performing ipsilateral (right), contralateral, protrusive and opening-closing jaw movements recorded at 2 velocities. Task phases were as follows: BEFORE, OUT, HOLDING, RETURN and AFTER. SMU onset thresholds were determined from the displacement (mm) of the lower mid-incisor point. Electrode location within 4 arbitrary muscle divisions was determined with computer tomography. Statistical tests: Spearman's correlations, Kruskal-Wallis tests; significance accepted at P < .05. RESULTS: A significant inverse relation occurred between velocity and threshold for the RETURN of the ipsilateral movement (n = 62 SMU thresholds), while a significant positive relation occurred for the OUT of the contralateral movement (n = 208); there were no significant associations for the protrusive (n = 131) and opening-closing (n = 58) tasks. Significant threshold differences occurred across the 4 muscle divisions only during the OUT of the contralateral and protrusive movements. Some evidence was provided for gender differences in MPt SMU properties. CONCLUSIONS: The absence of a significant inverse relation between velocity and SMU threshold for most recorded movements suggests the MPt acts as a stabilizer of the jaw in horizontal and opening-closing jaw movements.

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A man in his 60s with severe trismus was referred to our hospital. Based on computed tomography (CT), positron emission tomography/computed tomography (PET/CT), and biopsy, his initial diagnosis at another hospital was oropharyngeal cancer with cervical lymph node and distant metastases. After the review of the contrast-enhanced CT and reevaluated PET/CT images, we updated his diagnosis to left primary lung cancer that had metastasized to the cervical lymph nodes, bones, and skeletal muscles including the right medial pterygoid muscle. Since metastasis from primary lung cancer to the contralateral cervical lymph node is relatively rare, cervical lymph node metastases were thought to have originated from the metastatic lesion in the right medial pterygoid muscle. As metastases in the masticator muscles from lung cancer are rare, it is sometimes necessary to differentiate from primary head and neck lesions. Here, we report a rare case of lung cancer with the onset of trismus due to metastasis to the masticator muscle and perineural spread along the mandibular nerve.

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The study samples included 12 anatomical specimens taken from the fixed corpses of various gender and age. Pterygomandibular space topography was assessed by macro - and micropreparation methods. The landmarks for the universal way of mandibular anesthesia were defined associated with low risk of medial pterygoid muscle, lingual nerve, inferior alveolar neurovascular bundle damage. The study results allow increasing the efficiency and safety of anesthesia of the lower jaw teeth.

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PURPOSE: The purpose of this study was to examine changes in masseter and medial pterygoid muscles, ramus, condyle and occlusal force after bi-maxillary surgery in class II and III patients. SUBJECTS AND METHODS: The subjects were 42 patients (84 sides) who underwent sagittal split ramus osteotomy with Le Fort I osteotomy (21 class II cases: mandibular advancement and 21 class III cases: mandibular setback). The cross-sectional measurements of the masseter and medial pterygoid muscles, ramus and condyle were measured in horizontal plane images by computed tomography (CT), before and 1 year after the operation. Occlusal force and contact area were also recorded before and 1 year after the operation. RESULTS: Preoperatively, class II was significantly larger than class III in masseter width (P = 0.0068), masseter area (P < 0.0001) and medial pterygoid length (P < 0.0001). However, class II was significantly smaller than class III in medial pterygoid width (P < 0.0001). After 1 year, class II was significantly smaller than class III in masseter length (P = 0.0017). Class II was still larger than class III in medial pterygoid area after 1 year (P = 0.0343). Class II was significantly larger than class III in condylar angle pre-operatively (P < 0.0001) and after 1 year (P = 0.0006). After 1 year, class II decreased significantly more than class III in condylar thickness (P = 0.0020), condylar width (P < 0.0001) and condylar area (P < 0.0001). CONCLUSION: This study suggested that changes in the cross-sectional measurements of masseter and medial pterygoid muscles and the condyle differed between class II and class III patients, although occlusal force did not significantly change 1 year after surgery in both groups.

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OBJECTIVE: This study aimed to investigate the influence of decreased functional load on the medial pterygoid muscle during mastication in rabbits fed with a liquid-diet. MATERIALS AND METHODS: Medial pterygoid muscles from 54 rabbits (solid- and liquid-diet groups, n=48; unweaned group, n=6) were histochemically examined at 4, 9, 12, 18, and 33 weeks after birth. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were distinguished via mATPase staining. RESULTS: Significant increases in the diameters of all fiber types were seen up to 33 weeks of age in the solid-diet group; however, no significant increase was noted in fiber types I and IC, from 4 to 33 weeks of age, in the liquid-diet group. The proportion of slow fibers increased up to 12 weeks followed by an increase in the number of fast fibers in the solid-diet group, whereas in the liquid-diet group, the number of slow fiber declined after weaning. CONCLUSIONS: Liquid-diet consumption caused muscle fiber atrophy and an increase in the number of fast fibers during early developmental stages after weaning. Furthermore, the growth pattern of the medial pterygoid muscle in the liquid-diet group was different from that in the solid-diet group.

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The medial pterygoid muscle is a layered structure like the masseter muscle. This study aimed at investigating the regional differences in fiber type composition and fiber diameter of the medial pterygoid muscle in the rabbit from birth until 33 weeks of age. Histochemical analysis of the medial pterygoid muscle was performed during five developmental stages (4, 9, 12, 18, and 33 weeks after birth) in 30 male Japanese white rabbits. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were identified by mATPase staining. An increase in diameter was observed in fiber types I and IC until 9 weeks of age, and in fiber types IIC, IIA, IIAB, and IIB until 33 weeks of age. No significant differences in fiber diameter were noted in the different regions of the pterygoid muscle. Moderate fast to slow fiber type shifts occurred from weeks 4-12; thereafter, a rapid slow to fast fiber type shift was observed. Significant differences in fiber type composition based on regional differences were noted at 4 weeks of age. However, there was no difference in fiber type composition between regions at 33 weeks. In conclusion, it was clear that the diameter and proportion of fast fibers had increased even after reaching sexual maturity in rabbits. In addition, the medial pterygoid muscle tissues appeared to be homogenous at 33 weeks of age with very few differences between regions.

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INTRODUCTION: Surgical correction of the patients with mandibular asymmetry by bilateral sagittal split ramus osteotomy (BSSRO) creats remarkable results in the immediate post operative period, but it carries a high risk of relapse by powerful muscle forces and the osteotomized segments. To minimize this risk, literatures highlight the procedure of an intentional osteotomy and stripping of muscles. A prospective study was conducted in Government Dental College, Kottayam, Kerala, to assess the effect of intentional osteotomy of posterior part of distal segment and stripping of medial pterygoid muscle on the proximal segment on affected side in mandibular asymmetry patients treated with BSSRO. MATERIALS AND METHODS: 20 patients above 18 years with mandibular asymmetry underwent surgical correction by BSSRO setback and rotation. Clinical evaluation and postero anterior cephalogram (PA Ceph) were used to assess relapse. PA cephalogram taken post operatively at 2 weeks, 6 months and 1year were compared using cephalometric parameters by Grummons analysis to assess relapse. Paired t test and Chi-square test was used to analyse quantitative and qualitative parameters respectively with statistical significance of p < 0.05. RESULTS: Barring Methodological errors which is inevitable, the amount of relapse was not statistically significant with respect to dental midline, chin midline and frontal photograph. CONCLUSION: Intentional osteotomy of posterior part of distal segment and stripping of medial pterygoid muscle on the affected side can prevent relapse in patients who underwent surgical correction of mandibular asymmetry by BSSRO set back and rotation.

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The eustachian tube consists of 2 compartments: the Rüdinger's safety canal and the auxiliary gap. It is surrounded by a cartilaginous wall on the craniomedial side and a membranous wall on the inferolateral side. The eustachian tube cartilage is firmly attached to the skull base by the lateral and the medial suspensory ligaments, which are separated by the medial Ostmann fat pad. The function of the isometric tensor veli palatini muscle is modulated by hypomochlia, which have an influence on the muscular force vectors.

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Changes in cross-sectional area (CSA), volume (indicating muscle strength), and direction of the masseter and medial pterygoid muscles after surgical mandibular advancement were measured, along with the rotation of the condyles after bilateral sagittal split osteotomies (BSSOs) to advance the mandible. Measurements were done on magnetic resonance images obtained before and 2 years after surgery. CSA and volume were measured in five short-face and seven long-face patients (five males, seven females). Muscle direction was calculated in eight short-face and eight long-face patients (eight males, eight females). Short-face patients underwent BSSO only; long-face patients underwent combined BSSO and Le Fort I osteotomies. The CSA and volume decreased significantly (mean 18%) in all patients after surgery. The postoperative muscle direction was significantly more vertical (9°) in long-face patients. Rotations of the proximal segments (condyles) were minimal after 2 years. The results of this study showed that, after BSSO advancement surgery, changes in the masseter and medial pterygoid muscles are not likely to cause increased pressure on the condyles and nor are the minimal rotations of the condyles. It is concluded that neither increased muscle traction nor condylar rotations can be held responsible for progressive condylar resorption after advancement BSSO.

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Myositis ossificans is a rare disease that is characterized by bone deposition in the muscle or soft tissues. Myositis ossificans of the masticatory muscles is an uncommon finding. The condition is benign and results in heterotopic bone formation in the muscles of mastication, usually producing limitation of opening of the jaws. It is important to know the exact cause of the limitation of opening of the jaws for successful treatment. Computed tomographic scan and panoramic radiographs along with histological findings are essential diagnostic aids for evaluating conditions such as myositis ossificans. A rare case of myositis ossificans traumatica of temporalis and medial pterygoid muscle is presented here along with the discussion of clinical, radiological and histological features. The present case emphasizes not only on the importance of considering myositis ossificans in the differential diagnosis of limitation of opening of the jaws but also on the improvement of the overall mouth opening and treatment results.

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It has been known that the medial pterygoid muscle influences the mandibular functions related to mandibular movements. In addition, the muscle bundle of the medial pterygoid muscle influences the stability of a complete denture. Therefore, the topography of this muscle is clinically important. However, researches on the clinical anatomy related to the insertion area, and innervation, of this muscle were rare. Therefore, authors investigated the morphological and topographic characteristics of the medial pterygoid muscle by dissection of 31 Korean cadavers. The following are the results:The middle portion of the medial pterygoid muscle was the longest with the length of 59.4 degrees +/-7.1mm, and upper one third of the total length of the muscle was composed of tendon. When comparing the morphology of the insertion area of the medial pterygoid muscle and the masseter muscle in the mandibular angle region, there was no difference of the length of the insertion from the gonion to the superior margin of the insertion on the ramus. However, the length from gonion to the anterior margin of the insertion on the ramus in the masseter case was twice as long as the medial pterygoid muscle case. Insertion of the medial pterygoid was morphologically classified into six groups based on the insertion pattern and the mylohyoid groove. Type V, which the muscle fibers in the insertion of the medial pterygoid muscle were divided and did not invade the mylohyoid groove, were found the most (26.6%). Most of pterygoid branch of trigeminal nerve entered the medial pterygoid muscle through the posterior one third area or the posterior marginal area. The average length between hamulus and the region where the pterygoid branch of mandibular nerve entered the medial pterygoid muscle was 10.1mm. In conclusion, the anatomical relationship between the medial pterygoid muscle and the surrounding structures will be able to provide useful data for clinical applications.

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The purpose of this study was to evaluate the resistant force of medial pterygoid muscles against the mandibular advancement and distraction to anterior, and inquire into the relationship between medial pterygoid muscles and cephalometric variables. Sixty six patients with class III malocclusion underwent bilateral sagittal splitting of ramus with intraoralvertico-sagittal ramus osteotomy for mandibular set-back. The spring scale was used to measure the resistance of medial pterygoid muscles after splitting of ramus. Skeletaldental cephalometric analysis was made and statistic package was used for correlation between resistance and cephalometric variables. The resistant force of the right medial pterygoid muscle was greater than the left one in Koreans with class III malocclusion, and the force had a linear regression relationship with facial depth. The results suggested that facial depth has significant correlation with the resistance of medial pterygoid muscle, which can be acquired from patient's cephalometric analysis.

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The aim of the present article is to describe the mechanical components of the auditory tube and the role of these components in auditory tube function. Particular attention will be given to those aspects which have not been sufficiently dealt with in the past, such as the role of the isthmus region, the function of the lateral mucosal folds, the significance of the surfactant proteins and the pathophysiology of the patulous auditory tube. Special attention is given to the tensor veli palatini muscle and its physiology. Because of its isometric contraction, the function of this muscle depends on so-called hypomochlia changing the direction of its force. In the context of this article, the three hypomochlia involved are the pterygoid hamulus, Ostmann's fatty tissue and the medial pterygoid muscle.The so-called "Eppendorf-maneuver" is depicted for the first time.