Correlation between GLCM-based texture features of the lateral pterygoid muscle and cognitive function in patients with idiopathic normal pressure hydrocephalus: a preliminary report.

PURPOSE: The potential relationship between mastication ability and cognitive function in idiopathic normal pressure hydrocephalus (iNPH) patients is unclear. This report investigated the association between mastication and cognitive function in iNPH patients using the gray level of the co-occurrence matrix on the lateral pterygoid muscle. METHODS: We analyzed data from 96 unoperated iNPH patients who underwent magnetic resonance imaging (MRI) between December 2016 and February 2023. Radiomic features were extracted from T2 MRI scans of the lateral pterygoid muscle, and muscle texture parameters were correlated with the iNPH grading scale. Subgroup analysis compared the texture parameters of patients with normal cognitive function with those of patients with cognitive impairment. RESULTS: The mini-mental state examination score correlated positively with the angular second moment (P < 0.05) and negatively with entropy (P < 0.05). The dementia scale (Eide's classification) correlated negatively with gray values (P < 0.05). Gray values were higher in the cognitive impairment group (64.7 ± 16.6) when compared with the non-cognitive impairment group (57.4 ± 13.3) (P = 0.005). Entropy was higher in the cognitive impairment group (8.2 ± 0.3) than in the non-cognitive impairment group (8.0 ± 0.3) (P < 0.001). The area under the receiver operating characteristic curve was 0.681 (P = 0.003) and 0.701 (P < 0.001) for gray value and entropy, respectively. CONCLUSION: Our findings suggest an association between heterogeneity of mastication and impaired cognitive function in iNPH patients and highlight muscle texture analysis as a potential tool for predicting cognitive impairment in these patients.

The sphenopterygoid canal and pterygoid foramen.

BACKGROUND: In human anatomy, there are well-known the foramina of the greater sphenoidal wing, the foramen rotundum, the foramen ovale, the foramen spinosum, as well as the inconstant sphenoidal emissary foramen of Vesalius and the foramen of Arnold. Different canals are found in several species of rodents, such as the alisphenoid and sphenopterygoid (SPC) canals. METHOD: It was re-explored an archived computed tomography angiogram of a 60 y.o. female case. RESULTS: Bilateral superior recesses of the pterygoid fossae (SRPF) and a right SPC were found. The SRPF on each side penetrated the non-lamellar pterygoid root and superiorly reached the sphenoidal sinus wall. Upper fibres of medial pterygoid muscles were inserted into each SRPF. An unexpected SPC was found on the right side. It opened superiorly on the lateral side of the foramen rotundum and inferiorly at a pterygoid foramen in the superior end of the posterior margin of the lateral pterygoid plate. A sphenoidal emissary vein traversed that SPC to drain into the pterygoid plexus. CONCLUSION: The SRPF and SPC could also be found in humans. As the sphenoidal emissary veins are surgically relevant, they should not be further regarded as exclusively crossing the foramen of Vesalius but also the SPC.

Localization of Maxillary Artery for Cerebral Revascularization: L-Shaped Perpendicular Two-Step Drilling Technique Stretching from the Foramen Ovale to Rotundum.

BACKGROUND: The use of the maxillary artery (MA) as a donor has increasingly become an alternative method for cerebral revascularization. Localization difficulties emerge due to rich infratemporal anatomical variations and the complicated relationships of the MA with neuromuscular structures. We propose an alternative localization method via the interforaminal route along the middle fossa floor. METHODS: Five silicone-injected adult cadaver heads (10 sides) were dissected. Safe and effective localization of the MA was evaluated. RESULTS: The MA displayed anatomical variations in relation to the lateral pterygoid muscle (LPM) and the mandibular nerve branches. The proposed L-shaped perpendicular 2-step drilling technique revealed a long MA segment that allowed generous rotation to the intracranial area for an end-to-end anastomosis. The first step of drilling involved medial-to-lateral expansion of foramen ovale up to the lateral border of the superior head of the LPM. The second step of drilling extended at an angle approximately 90° to the initial path and reached anteriorly to the foramen rotundum. The MA was localized by gently retracting the upper head of the LPM medially in a posterior-to-anterior direction. CONCLUSIONS: Considering all anatomical variations, the L-shaped perpendicular 2-step drilling technique through the interforaminal space is an attainable method to release an adequate length of MA. The advantages of this technique include the early identification of precise landmarks for the areas to be drilled, preserving all mandibular nerve branches, the deep temporal arteries, and maintaining the continuity of the LPM.

Newly revealed anatomy of the bucinator muscle: An anatomical and histological study.

BACKGROUND: Current anatomical knowledge of the origin of the bucinator muscle (BM), i.e., long thin attachments on the maxilla and mandible and the pterygomandibular raphe (PMR), is not supported by anatomical dissection of this muscle. The aim of this study was therefore to investigate the detailed morphology of the BM and associated structures and to discuss its function. METHODS: The anatomy of the BM and related structures was investigated in 15 cadaveric heads using a surgical microscope and histological analysis. RESULTS: The inferior fibers of the BM originated from a small retromolar area (internal oblique line), which shared a common tendon with the deep tendon of the temporalis. The superior fibers of the BM originated from the maxillary tuberosity. The middle fibers originated the pterygoid hamulus. No PMR was identified in any of the specimens, but the border between the BM and superior pharyngeal constrictor muscle (SC) was clear because the muscle fibers followed different directions. Some horizontal fibers were continuous between the BM and SC. CONCLUSIONS: Our results suggest the need to revise established accounts of the origins of the bucinator (the maxillary tuberosity, conjoint tendon of the temporalis, and pterygoid hamulus without a pterygomandibular raphe. It also needs to be noted that some of its fibers merge directly with the SC.

Sensory innervation of masseter, temporal and lateral pterygoid muscles in common marmosets.

Myogenous temporomandibular disorders is associated with an increased responsiveness of nerves innervating the masseter (MM), temporal (TM), and lateral pterygoid muscles (LPM). This study aimed to examine sensory nerve types innervating MM, TM and LPM of adult non-human primate-common marmosets. Sensory nerves were localized in specific regions of these muscles. Pgp9.5, marker for all nerves, and NFH, a marker for A-fibers, showed that masticatory muscles were primarily innervated with A-fibers. The proportion of C- to A-fibers was highest in LPM, and lowest in MM. All C-fibers (pgp9.5+/NFH-) observed in masticatory muscles were peptidergic (CGRP+) and lacked mrgprD and CHRNA3, a silent nociceptive marker. TrpV1 was register in 17% of LPM nerves. All fibers in masticatory muscles were labeled with GFAP+, a myelin sheath marker. There were substantially more peptidergic A-fibers (CGRP+/NFH+) in TM and LPM compared to MM. MM, TM and LPM NFH+ fibers contained different percentages of trkC+ and parvalbumin+, but not trkB+ fibers. Tyrosine hydroxylase antibodies, which did not label TG, highlighted sympathetic fibers around blood vessels of the masticatory muscles. Overall, masticatory muscle types of marmosets have similarities and differences in innervation patterns.

Efecto de la dibucaína sobre la SERCA del músculo pterigoideo interno / Drug action of dibucaine on the SERCA from medial pterygoid muscle

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)

Macroscopic analysis of the insertion points of the lateral pterygoid muscle in adult individuals / Análisis macroscópico de los lugares de inserción del músculo pterigoideo lateral en individuos adultos

SUMMARY: The lateral pterygoid muscle (LPM) is intimately related with the temporomandibular joint (TMJ), playing an important role in its physiology. This makes it of interest to researchers who investigate temporomandibular disorders. The literature indicates that anatomical variations exist in the insertion of the superior fascicle of the LPM. Imaging and cadaver studies have revealed that the LPM may present an accessory fascicle. The study object was to carry out macroscopic analysis of the LPM, examining the origin and insertion of its superior and inferior fascicles. The study used 38 half-heads of adult individuals fixed in formaldehyde 10 %. To carry out macroscopic analysis of the LPM, an initial incision was made along the lower margin of the zygomatic arch; the origin of the masseter muscle was then dissected, separating its insertion on the lateral face of the mandibular ramus and retracting the muscle to posteroinferior. Two incisions were made on the zygomatic arch and the insertion of the temporal muscle on the coronoid process was identified with dissection pincers; it was dissected to gain access to the infratemporal fossa and the two fascicles of the LPM. The superior fascicle (SF) originated on the infratemporal face of the greater wing of the sphenoid, and on the superior third of the lateral face of the lateral lamina of the pterygoid process of the sphenoid in 26 samples. In 12 samples, it originated on the greater wing of the sphenoid and the infratemporal crest of the sphenoid. Type I insertion was found in 20 samples, Type II in 6 samples and Type III in 12 samples. In all the samples analysed, the inferior fascicle (IF) originated on the inferior two thirds of the lateral face of the lateral lamina of the pterygoid process and on the lateral face of the pyramidal process of the palatine, with insertion on the pterygoid fovea. The accessory fascicle (AF) of the LPM was present in 6 samples. The AF originated on the greater wing of the sphenoid in 2 cases and inferior to the superior fascicle in 4 cases; its insertion was on the capsular disc complex in all cases. The results obtained in our study contribute anatomical data on the LPM in Brazilian adult individuals, with evaluation of its insertion points.

El músculo pterigoideo lateral (MPL) presenta íntima relación con la articulación temporomandibular (ATM) y desempeña un rol importante en la fisiología de esta articulación, despertando el interés de investigadores que se dedican al estudio de los trastornos temporomandibulares. La literatura señala que existen variaciones anatómicas del MPL, con respecto a la inserción del fascículo superior. Los estudios cadavéricos e imagenológicos han revelado que el MPL puede presentar un fascículo accesorio. El objetivo del estudio fue realizar un análisis macroscópico del MPL, examinando el origen e inserción de sus fascículos superior e inferior. Se utilizaron 38 hemicabezas de individuos adultos fijadas en formaldehído al 10 %. Para realizar el análisis macroscópico del MPL se realizó inicialmente una incisión a lo largo del margen inferior del arco cigomático, luego se seccionó el origen del músculo masétero separando su inserción en la cara lateral de la rama de la mandíbula, retrayendo al músculo en sentido posteroinferior. Se hicieron dos cortes en el arco cigomático y con pinzas de disección se identificó la inserción del músculo temporal en el proceso coronoides, el cual se seccionó para ingresar a la fosa infratemporal y acceder a ambos fascículos del MPL. El fascículo superior (FS) del MPL se originó en la cara infratemporal del ala mayor del esfenoides y en el tercio superior de la cara lateral de la lámina lateral del proceso pterigoides del esfenoides en 26 muestras. En 12 muestras se originó en el ala mayor del esfenoides y cresta infratemporal del esfenoides. Con relación a su inserción, se encontró el Tipo I en 20 muestras; el Tipo II en 6 muestras y el Tipo III en 12 muestras. En todas las muestras analizadas el origen del fascículo inferior (FI) del MPL fue en los dos tercios inferiores de la cara lateral de la lámina lateral del proceso pterigoides y en la cara lateral del proceso piramidal del palatino insertándose en la fóvea pterigoidea. El fascículo accesorio (FA) del MPL estuvo presente en 6 muestras. El FA se originó en el ala mayor del esfenoides en 2 casos e inferior al fascículo superior en 4 casos y su inserción, en el complejo disco capsular en todos los casos. Mediante los resultados obtenidos en nuestro estudio estamos aportando datos anatómicos en relación al MPL en individuos brasileños adultos, evaluándolo con respecto a sus lugares de inserción.

Evaluation of the presence of the third head on the lateral pterygoid muscle in adult individuals / Evaluación de la presencia de la tercera cabeza del músculo pteriogoideo lateral en individuos adultos

SUMMARY: The lateral pterygoid muscle (LPM) is one of the muscles involved in jaw movements, and is therefore of great importance in the physiology of the temporomandibular joint. This muscle has classically been considered to have two heads, superior and inferior, however previous studies have indicated the presence of a third head (TH). The object of this research was therefore to evaluate, through a study in cadavers, the presence of the third head of the LPM and its relation with the joint disc of the TMJ in adult individuals. The study used 30 half-skulls of adult individuals, 11 right side and 19 left side. The number of heads on each LPM was analysed, with the length and thickness of each. The Chi-squared, Mann-Whitney U, Kruskall-Wallis and Spearman's correlation coefficient tests were applied, with a significance threshold of 5 %. The TH of the LPM was present in 20 % of the samples. Statistically significant differences were found in the thickness of the superior head (SH) vs. the inferior head (IH) (p<0.001) and between TH vs. SH and TH vs. IH (p=0.010). No correlation was found between the thickness of the heads or in their lengths. The LPM most frequently presents two heads, superior and inferior. The TH is an anatomical variation that may be present in 20 % of cases. The IH usually presents the greatest thickness. The use of cadavers is a good method for analysing the presence of the TH and the morphometry of the various heads of the LPM.

RESUMEN: El músculo pterigoideo lateral (MPL) es uno de los músculos involucrados en los movimientos mandibulares y por consiguiente tiene una gran importancia en la fisiología de la articulación temporomandibular (ATM). Clásicamente se ha considerado como un músculo que presenta dos cabezas, una superior y otra inferior, sin embargo estudios anteriores han señalado la presencia de una tercera cabeza (TC). El objetivo fue evaluar, mediante estudio en cadáveres, la presencia de la tercera cabeza del MPL y su relación con el disco articular de la ATM de individuos adultos. Se utilizaron 30 hemicabezas de individuos adultos, 11 del lado derecho y 19 en el lado izquierdo. Se analizó el número de cabezas, longitud y grosor de cada cabeza. Se aplicaron las pruebas de chi-cuadrado, U-Mann-Whitney, Kruskall-Walis y coeficiente de correlación de Spearman, con umbral de significación de 5 %. La TC del MPL estuvo presente en 20 % de las muestras. Se encontraron diferencias estadísticas significativas para el grosor del la cabeza superior (CS) vs. cabeza inferior (CI) (p<0,001) y entre TC vs. CS y TC vs. CI (p=0,010). No se encontró correlación entre el grosor de las cabezas o para la longitud de las cabezas. El MPL se presenta más frecuentemente con dos cabezas, una superior y otra inferior. La TC es una variación anatómica que puede estar presente en un 20 % de los casos. La CI suele ser la que presenta mayor grosor. En cuanto a los métodos para análisis de presencia de la TC y morfometría de las distintas cabezas del MPL el uso de cadáveres representa una buena alternativa.

Expression of myosin heavy chain isoform mRNA transcripts in the masseter and medial pterygoid muscles / Expresión de transcripciones de ARNm de isoforma de cadena pesada de miosina en los músculos masetero y pterigoideo medial

SUMMARY: Both the masseter and medial pterygoid muscles elevate the mandible, raising the lower jaw by acting simultaneously on the lateral and medial surfaces of the mandibular ramus. Nevertheless, electromyographic studies indicate that these muscles, as well as the superficial and deep heads of the masseter, act in a different way during mastication. We have analyzed by real time quantitative polymerase chain reaction (RT-qPCR) the expression of myosin heavy chain (MHC) isoforms in the masseter and medial pterygoid muscles in humans in order to identify possible differences in the expression patterns that may be related to functional differences identified with electromyography. Our findings indicate that the expression pattern of MHC isoforms in the two muscles is characteristic of fast and powerful phasic muscles. We have also observed a high percentage of expression of the MHC-IIx isoform and the expression of the MHC-M isoform at the mRNA level in both muscles, an isoform that does not translate into protein in the masticatory muscles of humans. The high percentage of expression of the MHC-IIx isoform in humans can be related to a high contractile speed of the masseter and medial pterygoid in humans. On the other hand, the low percentage of expression of the MHC-M isoform at the mRNA level in both muscles can be related to the complex evolutionary process that has reduced the size and force of the masticatory muscles in humans.

RESUMEN: Los músculos masetero y pterigoideo medial elevan la mandíbula actuando de forma simultánea sobre las caras lateral y medial de su rama. Sin embargo, los estudios electromiográficos indican que estos dos músculos actúan de forma diferente durante la masticación, de la misma forma que lo hacen las porciones superficial y profunda del músculo masetero. En el presente estudio hemos analizado mediante PCR en tiempo real la expresión de las isoformas de la cadena pesada de la miosina o myosin heavy chain (MHC) en los músculos masetero y pterigoideo medial en humanos, con la finalidad de identificar diferencias en los patrones de expresión que se puedan relacionar con las diferencias funcionales identificadas con la electromiografía. Nuestros resultados indican que el patrón de expresión de las isoformas de la MHC en los dos músculos es la característica de los músculos rápidos y potentes. También hemos observado un elevado porcentaje de expresión de la isoforma MHC-IIx y la expresión a nivel de ARNm de la isoforma MHC-M en los dos músculos, una isoforma que no se detecta a nivel de proteína en los músculos masticadores humanos. El elevado porcentaje de expresión de la isoforma MHC-IIx que hemos observado se puede relacionar con una elevada velocidad de contracción de los músculos masetero y pterigoideo medial en los humanos. Por otro lado, el bajo porcentaje de expresión de la isoforma MHC-M a nivel de ARNm en ambos músculos se puede relacionar con los procesos evolutivos complejos que han reducido el tamaño y la fuerza de los músculos masticadores en los humanos.

Análisis morfológico y funcional del músculo pterigoideo lateral: una revisión de la literatura / Morphological and functional analysis of the lateral pterygoid muscle: a review of the literature

RESUMEN: El músculo pterigoideo lateral (MPL) es una estructura compleja y variable, poder determinar su anatomía exacta, relaciones vecinas, origen e inserciones, ayuda a los clínicos a comprender de mejor forma su función en el sistema estomatognático. En esta revisión se busca analizar la literatura que ayude a esclarecer la función antagónica de las cabezas del músculo pterigoideo lateral, desde un punto de vista nervioso, la descripción de su origen e inserciones y sus posibles variaciones anatómicas, además del análisis de sus funciones evaluado a través de la literatura tradicional y compararlo con lo descrito en artículos originales. Se analizaron diferentes bases de datos electrónicos y libros, con criterios de inclusión e exclusión claramente definidos, la lectura fue llevada a cabo por dos investigadores de manera independiente consultando de ser necesario con un tercer investigador. Esta revisión incluyo un total de 11 artículos y 4 libros atingentes a nuestro tema de estudio. Se expusieron los resultados a través de tablas de extracción de datos, que incluyó las funciones, inervación, el origen e inserción y las variaciones anatómicas del MPL. Nuestros resultados muestran que se identificaron claramente los elementos comunes de origen del MPL, pero su inserción mostró variaciones entre los distintos estudios, tanto en el porcentaje de fibras unidas como a los elementos anatómicos insertados. Considerando las funciones antagónicas de sus dos cabezas, autores lo han descrito como dos músculos diferentes, sin embargo desde un punto de vista nervioso, esta teoría no es apoyada. Finalmente comprender las funciones del MPL durante su acción es complejo, ya que la gran mayoría de los estudios disponibles utilizan cadáveres o electromiografía por lo que creemos que el desarrollo de metodologías menos invasivas y dolorosas, ayudarían a comprender el comportamiento de este músculo durante su función y como las variaciones anatómicas influyen en estas.

SUMMARY: The Lateral Pterygoid Muscle (LPM) is a complex and variable structure. Being able to determine its exact anatomy, neighboring relationships, origin and insertions, helps clinicians to better understand its function in the stomatognathic system. This review seeks to analyze the literature, in order to clarify the antagonistic function of the lateral pterygoid muscle heads, from a nervous point of view. Furthermore, the description of its origin, aspects of insertions and possible anatomical variations, its functions as reported in traditional literature, are analyzed and compared with original articles. Different electronic databases and books were analyzed, with designated inclusion and exclusion criteria. Two researchers independently reviewed the articles, whennecessary a third researcher resolved any differences. This review includes a total of 11 articles and 4 books related to our study topic. Results were reported using data extraction tables, which included functions, innervation, origin and insertion, and anatomical variations of the LPM. Our results show that the common elements of origin of LPM were clearly identified, but their insertion showed variations between the different studies, both in the percentage of fibers joined and the anatomical elements inserted. Considering the antagonistic functions of the two heads, authors have described it as two different muscles. However from a nervous point of view, this theory is not supported. Finally, understanding the functions of the LPM during its action is complex, since most studies available use cadavers or electromyography. Therefore, we believe that the development of less invasive and painful methodologies, would help to understand the influence of anatomical variations on the function of this muscle.

Ultrastructural analysis of masseter and left medial pterigoid muscles, after unilateral mandibular molar extraction: experimental study / Análisis ultrastructural de los músculos masetero y pterigoideo medial izquierdo, después de la extracción molar mandibular unilateral: estudio experimental

Twelve adult male Wistar rats (220 g average weight) were divided in 3 experimental groups: GI -15. GII ­ 30 and GIII ­ 60 days, after mandibular molar extraction, with three experimental animals and one control per group. Qualitatively, ultrastructural changes of protein filaments from myofibrils of these muscles and ipsilateral to the extractions were observed. Ultrastructure asymmetry and disorganization of Z line and I band, in the experimental group GII, of Medial Pterigoid muscle (MPT) were observed. The temporomandibular dysfunction, stimulated by the unilateral extractions of mandibular molars in rats may lead to modifications in the Z line and I band, which showed to be sensitive to this dysfunction. Changes in the MPT muscle, probably related to its own functional characteristics and major participation in the dynamics of mastication, compared to Masseter were also observed. However, the muscular fibres seem to adapt to the new conditions along the experiment.

Doce ratas Wistar machos adultos (220 g de peso promedio) se dividieron en 3 grupos experimentales: GI - 15, GII - 30 y GIII - 60 días, después de una extracción molar mandibular. En cada grupo se dispusieron tres animales experimentales y un animal como control. Cualitativamente, se observaron cambios ultraestructurales de filamentos de proteínas de miofibrillas de estos músculos masticadores ipsilaterales a las extracciones. Se observó asimetría de la ultraestructura y desorganización de la línea Z y la banda I, en el músculo pterigoideo medial del grupo experimental GII, (MPT). La disfunción temporomandibular, estimulada por las extracciones unilaterales de los molares mandibulares en ratas, puede conducir a modificaciones en la línea Z y en la banda I, que mostraron ser sensibles a esta disfunción. Los cambios en el músculo pterigoideo medial, se debieron, probablemente, con sus propias características funcionales y una mayor participación en la dinámica de la masticación, en comparación con el músculo masetero. Sin embargo, las fibras musculares parecen adaptarse a las nuevas condiciones a lo largo del experimento.

Análise da angulação das lâminas medial e lateral do processo pterigoide do osso esfenoide pela tomografia computadorizada / Analysis of the angle between the medial and lateral blades of the pterygoid process of the sphenoid bone for computed tomography

Determinadas situações de alteração da normalidade envolvem a simetria óssea dos processos pterigoides como a hemi-hiperplasia que é uma anomalia de desenvolvimento caracterizada pelo crescimento assimétrico de uma ou mais partes do corpo. A relação entre o volume de músculos da mastigação e estruturas ósseas pode ser estudada em doentes com e sem assimetria facial. A importância do conhecimento da anatomia radiográfica para a interpretação de afecções ósseas foi embasada no conhecimento anatômico do padrão de normalidade, principalmente no tocante a estruturas que servem de inserção aos músculos da mastigação. Esta pesquisa tem por objetivo determinar da angulação das lâminas medial e lateral do processo pterigoide do osso esfenoide, por meio da tomografia computadorizada helicoidal. Neste trabalho, em uma amostra que contou com 52 exames de tomografias computadorizadas, foi mensurado o ângulo entre as lâminas medial e lateral do processo pterigoide do osso esfenoide. Foram obtidos ângulos com média de 41,33° do lado D e 41,66° do lado E

The aim in this research is to determine the angle formed by the medial and lateral blades of the pterygoid process of the sphenoid bone through helical CT. Certain situations involve alteration of normal bone symmetry of the pterygoid processes as hemihyperplasia which is a developmental anomaly characterized by asymmetric growth of one or more body parts. The relationship between the volume of masticatoty muscles and bony structures may be studied in patients with and without facial asymmetry. The knowledge of radiographic anatomy for the interpretation of bone infections is based on knowledge of the normal anatomical structures especially regarding those that serve as suport to the masticatoty muscles. In this study, in 52 helical CT exames, the angle between the blades of the medial and lateral pterygoid process of the sphenoid bone were measured. The mean angles found were 41.33° to the right side and 41.66° to the left side

Influencia del músculo pterigoideo lateral en el crecimiento del cartílago condilar mandibular / Influence of the lateral pterygoid muscle on the growth of the mandibular condilar cartilage / Influência do músculo pterigóideo lateral no crescimento cartilagem condilar na mandíbula

A finales del siglo pasado se desarrolló un modelo para explicar observaciones clínicas relacionadas con el crecimiento mandibular, según el cual el músculo pterigoideo lateral (LPM) era uno de los principales moduladores de la diferenciación de las células mesenquimales del cóndilo mandibular a condroblastos u osteoblastos y por lo tanto del crecimiento del cartílago condilar mandibular (CCM). Dos grandes componentes eran los pilares fundamentales del modelo: el humoral y el mecánico. En la actualidad, el componente humoral estaría dado por factores de crecimiento como el IGF-I, el FGF-2 y el VEGF, los cuales parecen estar involucrados en el crecimiento mandibular. Debido a que el músculo esquelético tiene un papel como órgano secretor de ellos, se abre la posibilidad de que el LPM regule el crecimiento del CCM por un mecanismo paracrino o endocrino mediado por estos factores. El componente mecánico nació de las observaciones de que tanto el flujo sanguíneo dentro de la articulación temporomandibular como la acción de la almohadilla retrodiscal en el crecimiento del CCM depende, en parte, de la actividad contráctil del LPM. A pesar de que hay evidencia de que el LPM se activa en situaciones de adelantamiento mandibular, no hay consenso sobre si esto estimula el crecimiento del CCM. En esta revisión se discuten los aportes y limitaciones de los trabajos relacionados con el crecimiento mandibular y se propone un modelo que integra la información disponible para explicar el papel del LPM en el crecimiento del CCM.

At the end of the last century, a model to explain clinical observations related to the mandibular growth was developed. According to it, the lateral pterigoid muscle (LPM) was one of the main modulators of the differentiation of mesenquimal cells inside the condyle to condroblasts or osteoblasts, and therefore of the growth of the mandibular condilar cartilage (CCM). The main components of the model were the humoral and the mechanical. Nowadays, the humoral would include growth factors such as IGF-I, FGF-2 and VEGF, which seem to be involved in mandibular growth. Since skeletal muscle can secrete these growth factors, there is a possibility that LPM modulates the growth of CCM by a paracrine or endocrine mechanism. The mechanical component derived from the observations that both the blood flow inside the temporomandibular joint and the action of the retrodiscal pad on the growth of the CCM, depend, in part, on the contractile activity of the LPM. Despite the fact that there are some results suggesting that LPM is activated under conditions of mandibular protrusion, there is no full agreement on whether this can stimulate the growth of CCM. In this review, the contributions and limitations of the works related to mandibular growth are discussed and a model which integrates the available information to explain the role of the LPM in the growth of the CCM is proposed.

No fim do século passado desenhou-se um modelo para esclarecer as observações clínicas envolvidas no crescimento da mandíbula, no qual o músculo pterigoideo lateral (LPM) foi um dois moduladores principais da diferenciação das células messenquimais do côndilo mandibular em condroblastos ou osteoblastos e porém do crescimento da cartilagem condilar mandibular (CCM). Dois componentes principais possui o modelo: o humoral e o mecânico. Na atualidade, há evidência que o componente humoral é dado pelos fatores de crescimento IGF-1, IGF2 e VEGF que estimulam diretamente o crescimento mandibular. Devido a que o músculo esquelético pode desempenhar uma função endócrina fica aberta a possibilidade que o LPM regule o crescimento do CCM por mecanismos paracrinos ou autocrinos, mediante a secreção desses fatores de crescimento que estimulam diretamente o crescimiento mandibular. O componente mecânico é derivado das observações do que tanto o fluxo sanguíneo na articulação tempo-mandibular quanto a ação da almofadinha retro-discal no crescimento do CCM, dependem parcialmente da atividade contrátil do LPM. Embora, há evidências que o LPM é ativado pelo adiantamento mandibular, ainda não há consenso sob seu possível papel na estimulação do crescimento do CCM. Esta revisão tem o objetivo de discutir as evidencias e limitações de trabalhos relativos ao crescimento mandibular e propõe-se um modelo que integra a informação disponível para explicar a função do IPM no crescimento do CCM.

Effect of articaine on calcium transport in sarcoplasmic reticulum membranes isolated from medial pterygoid muscle

Local anesthetics used in dentistry have myotoxic effects. Articaine, also known as carticaine, is one of the local anesthetics most widely used in clinical dentistry. The aim of this work was to describe its effect on the sarcoplasmic reticulum Ca-ATPase isolated from medial pterygoid muscle. Ca-ATPase enzymatic activity was determined by a colorimetric method and ATP-dependent calcium uptake with a radioisotopic technique. Articaine inhibited both Ca-ATPase activity and calcium uptake in a concentrationdependent manner. Both inhibitory effects became evident at articaine concentrations lower than those employed in clinical dentistry. Half-maximal inhibitory concentrations (Ki) were 15.1± 1.8 mM (n = 6) and 25.2 ± 1.6 mM (n = 6) for enzymatic activity and calcium uptake, respectively. Preincubation of sarcoplasmic reticulum membranes with articaine enhanced Ca-ATPase activity in the absence of calcium ionophore, suggesting an ionophoriclike effect of the local anesthetic. We conclude that the inhibitory effect of articaine on the sarcoplasmic reticulum Ca-ATPase isolated from medial pterygoid muscle is due to a direct interaction of the anesthetic with the enzyme and to the increased membrane permeability to calcium induced by this drug.

Los anestésicos locales de uso odontológico tienen efectos miotóxicos. La carticaína, también conocida como articaína, es uno de los anestésicos locales más usados en la clínica odontológica actual. El objetivo del trabajo fue describir el efecto de la carticaína sobre la Ca-ATPasa del retículo sarcoplásmico aislada del músculo pterigoideo interno. La actividad enzimática de la bomba de calcio se determinó por un método colorimétrico y se utilizó un método radioisotópico a fin de determinar la captación de calcio dependiente de ATP. La carticaína inhibió la actividad enzimática y la captación de calcio en función de su concentración. Ambos efectos se observaron a concentraciones de carticaína menores a las utilizadas en la clínica. Las concentraciones de carticaína necesarias para inhibir la actividad Ca-ATPásica y la captación de calcio a la mitad de su valor máximo (Ki) fueron 15.1 ± 1.8 mM (n = 6) y 25.2 ± 1.6 mM (n = 6) respectivamente. La preincubación con carticaína de las membranas de retículo sarcoplásmico del músculo pterigoideo interno, en ausencia de ionóforo de calcio, incrementó la actividad de la enzima, evidenciando un efecto ionofórico del anestésico local. Concluimos que el efecto inhibitorio de la carticaína sobre la Ca-ATPasa de retículo sarcoplásmico del músculo pterigoideo interno se debe a la acción directa del anestésico local sobre la enzima y al incremento de la permeabilidad de la membrana del retículo sarcoplásmico al calcio inducido por esta droga.

Percentage of lateral pterygoid muscle inserted in the disc of human temporomandibular joint / Porcentaje del músculo pterigoideo lateral inserto en el disco de la articulación temporomandibular humana

Insertion of the upper head of the lateral pterygoid (UHLP) in the temporomandibular joint disc (TMJ) has been linked to anterior displacement of the disc and temporomandibular disfunction. The aim of this study was to determine in human adults, the percentage of muscle fiber in the upper head of the lateral pterygoid muscle inserted in the articular disc. A systematic review of the literature was designed beginning with articles published in Medline, Lilacs and Scielo data bases between the years 1990 and 2010. Key words "Lateral Pterygoid Muscle" and Pterygoid Lateral Muscle" were used, and the term MeSH "Pterygoid Muscle" with Boolean OR "Lateral Ptrerygoid Muscle" AND "Insertion" and the free terms "Pterygoid Lateral Muscle Disc Articular" and "Pterygoid lateral Muscle Meniscus". Of the 156 articles obtained and analyzed, 18 articles meeting eligibility criteria were selected. Based on those articles the percentage of insertion of the CSPL in the TMJ disc was evaluated, each one was subsequently assigned a level of evidence according to OCEBM Oxford Centre Evidence Based Medicine. Only four articles answered the research inquiry, three studies were histological and one used imaging techniques with cross section slices with an adequate evidence level (1B). However, results differed with insertion percentages from 2 percent to 69.8 percent being reported in the superior head of the lateral pterygoid muscle in the articular disc.

La actividad de la inserción de la cabeza superior del pterigoideo lateral (CSPL) en el disco de la articulación temporomandibular (ATM) ha sido vinculada al desplazamiento anterior del disco y disfunción temporomandibular. El propósito de este estudio fue determinar el porcentaje de fibras musculares de la cabeza superior del músculo pterigoideo lateral que se insertan en el disco articular, en humanos adultos. Se diseñó una revisión sistemática de la literatura a partir de artículos primarios publicados en las bases de datos Medline, Lilacs y Scielo entre los años 1990 y 2010. Se utilizaron las palabras clave "Músculo Pterigoideo Lateral" y "Pterygoid Lateral Muscle", el Término MeSH: "Pterygoid Muscle" con los boleanos OR "Lateral Pterygoid Muscle" AND "Insertion" y los Términos Libres: "Pterygoid Lateral Muscle Disc Articular" y "Pterygoid lateral Muscle Meniscus". Se obtuvieron 156 artículos, los cuales fueron analizados y se seleccionaron 18 que cumplieron con los criterios de elegibilidad. En base a estos artículos se evaluó el porcentaje de inserción de la CSPL en el disco de la ATM, posteriormente a cada uno se les otorgó un nivel de evidencia de acuerdo a la clasificación de Oxford Centre Evidence Based Medicine (OCEBM). Solo 4 artículos respondieron a la pregunta de investigación, 3 estudios fueron histológicos y 1 imagenológico, todos con diseños de cortes transversales con buen nivel de evidencia (1b). Sin embargo los resultados fueron disímiles, reportándose porcentajes de inserción del 2 al 69,8 por ciento de la cabeza superior del pterigoideo lateral en el disco articular.

Dental broken needle migration to the skull base: a case of dental broken needle migration to the skull base: anatomical considerations and prevention

Introduction: the needle fracture during the inferior alveolar nerve block is not a common accident, but whenit occurs can cause great inconvenience to the professional and patient, because the surgical removal shouldonly be performed without risk of sequelae to the patient. Aim: relate a case of broken dental needle duringinferior alveolar nerve block and the needle fragment dislocation to the skull base becoming impossible itssurgical removal. Described preventive procedures to avoid that complication with anatomical considerationsrelated to the inferior alveolar nerve block. Case report: a young female, 18 years old required care afterfracture of the dental needle during inferior alveolar nerve anesthesia. She was submitted to CT scan thatdetermined the impossibility of surgical removal of the fragment because it has migrated to the skull basebecoming close to vital anatomic structures because its could produce irreparable sequelae such loss of tonguesensation and movement of the lip. A conservative treatment was offered. Conclusions: surgical removal ofits instrument should be correctly evaluated to avoided irreparable sequelae to the patient. The knowledgeof anatomical structures in the pterigomandibular region may reduce the risk of injury to nerves and anotherstructures and prevent further complications.

Anatomical study of the pterygospinous and pterygoalar bony bridges and foramens in dried crania and its clinical relevance / Estudio anatómico de los puentes óseos y forámenes pterigoespinoso y pterigoalar en cráneos secos y su relevancia clínica

The ossification of the intrinsic ligaments of the sphenoid bone has been reported in the literature. The presence of bony bridges by ossification of the pterygospinous and pterygoalar ligaments has clinical significance in the infratemporal fossa contents. The purpose of this study is to analyze the prevalence of ossification of these ligaments and assess morphometrically the pterygospinous (Civinini's) and pterygoalar (crotaphitico-buccinatorius) foramens. A total of 312 human skulls from the collection of Universidade Federal de São Paulo (UNIFESP) were used to assess the presence of total or partial ossification in pterygospinous (Types I and II) and pterygoalar (Types III and IV) ligaments. Of the sample, 37.18 percent had some degree of ossification; in Type I, ossification was found in 1.6 percent, while Types II, III and IV had 13.14, 3.84, and 22.43 percent, respectively. The pterygospinous foramen presented an average diameter between 10.626ð7.366 mm, whereas for the pterygoalar foramen it was between 5.202ð3.793 mm. The presence of these formations must be considered in the therapeutic procedures that are performed in the infratemporal region, in assessing pain affecting the territory innervated by the mandibular nerve.

La osificación de los ligamentos intrínsecos del hueso esfenoides ha sido reportada en la literatura. La presencia de puentes óseos por osificación de los ligamentos pterigoespinoso y pterigoalar tiene importancia clínica debido a las relaciones que éstas formaciones establecen con el contenido de la fosa infratemporal. El propósito de este estudio fue analizar la prevalencia de la osificación de estos ligamentos y evaluar morfométricamente los forámenes pterigoespinoso (Cinivini's) y pterigoalar (crotaphitico-buccinatorius). Se utilizaron 312 cráneos humanos de la colección de la UNIFESP, se evaluó la presencia de osificación total o parcial de los ligamentos pterigoespinoso (Tipos I y II) y pterigoalar (Tipos III y IV). Un 37,18 por ciento de la muestra presentó algún grado de osificación, el tipo I se encontró en un 1,6 por ciento por ciento, el tipo II en un 13,14 por ciento, el tipo III en un 3,84 por ciento por ciento y el tipo IV en un 22,43 por ciento. El foramen pterigoespinoso presentó un diámetro medio de entre 10,626 ð 7,366 mm, mientras que para el foramen pterigoalar estuvieron entre 5,202 ð 3,793 mm. La presencia de estas formaciones debe ser considerada en los procedimientos terapéuticos que se realicen en la región infratemporal y en la evaluación de cuadros dolorosos que afectan al territorio inervado por el nervio mandibular.

Anterior disc displacement and the superior head of lateral pterygoid muscle: a case-control study / Desplazamiento discal anterior y la cabeza superior del músculo pterigoideo lateral: un estudio caso-control

The objective of this study was to assess the association between an increase in the proportion of the superior head of the lateral pterygoid muscle (SHLP) inserted into the temporomandibular joint (TMJ) disc and the presence of anterior disc displacement diagnosed by using MRI. We analyzed 75 images of patients with anterior displacement and 75 controls with normal relationship between the mandibular head and the articular tubercle also diagnosed by MRI. Levels of insertion were measured. Descriptive and analytic statistics were calculated. Analyses of differences were made by Fischer's exact test and also were calculated clinical significance (OR, CI = 95 percent). The average insertion of SHLP was 71.14 percent (SD 14.13) in controls and 67.80 percent (SD.16.23) in cases group. The only relationship that presented a significant association (OR 5.61) was found when comparing subjects with a percentage of inserting the disc into the SHLP at 50 percent with those who had higher levels of insertion (50 percent). Our results suggest that the highest percentage of insertion serves as a protective factor for anterior disc displacement, probably due to greater control of neuromuscular activity.

El objetivo de este estudio fue evaluar la asociación entre el aumento de la proporción de la cabeza superior del músculo pterigoideo lateral (CSPT) insertado en la articulación temporomandibular (ATM) y la presencia de desplazamiento discal anterior diagnosticado mediante resonancia magnética. Se analizaron 75 imágenes de pacientes con desplazamiento discal anterior y 75 controles con una relación normal entre la cabeza de la mandíbula y el tubérculo articular, también diagnosticada por resonancia magnética. Los niveles de inserción fueron medidos. La estadística descriptiva y analítica fueron calculadas. Los análisis de las diferencias se hicieron por la prueba exacta de Fischer, y también se calculó la significancia clínica (OR, IC=95 por ciento). La inserción media de la CSPT fue 71,14 por ciento (DS 14,13) en los controles y 67,80 por ciento (SD 16,23) en los casos de grupo. La única relación que presentó una asociación significativa (OR 5,61) se encontró al comparar los sujetos con un porcentaje de inserción en la CSPT 50 por ciento con aquellos que tenían niveles más altos de inserción (50 por ciento). Nuestros resultados sugieren que el mayor porcentaje de inserción sirve como un factor de protección para el desplazamiento discal anterior, probablemente debido a un mayor control de la actividad neuromuscular.

Superior head of the lateral pterygoid muscle inserting in asymptomatictemporomandibular joints / Inserción de la cabeza superior del músculo pterigoideo lateral enarticulaciones temporomandibulares asintomáticas

The constitution and shape of superior head of the lateral pterygoid muscle (SHLP) inserts remains a topic of interest in the literature. The purpose of this study was to analyze by magnetic resonance imaging (MRI) the temporomandibular joint (TMJ) of individuals without signs of temporomandibular dysfunction. One hundred seventy-eight MRI images of one hundred and three patients were utilized, and the surface and percentage of the SHLP insert into the articular disc and condilar process was determined. In women, the average insertion into the disc was found to be between 5.7–5.5mm (SD 1.5–1.3), corresponding to 69.8–70.7 percent of the SHLP. In men, the average insertion into the disc was between 6.2–6.12mm (SD 1.8–1.9), or 68.9–74.2 percent. There were no differences in terms of the sex of the patients or the side of the joint. We found a significant percentage of SHLP fibers embedded in the disc of asymptomatic TMJs, and its role in theanterior disc displacement and the development of the temporomandibular dysfunction should be revised.

La constitución y la forma de inserción de la cabeza superior del músculo pterigoideo lateral (CSMPL) sigue siendo un tema de interés en la literatura. El objetivo de este estudio fue analizar mediante resonancia nuclear magnética (RNM) la articulación temporomandibular (ATM) de individuos sin signos de disfunción temporomandibular. Fueron utilizadas 178 imágenes de RNM pertenecientes a 103 pacientes. Se determinó la superficie y porcentaje de la inserción de la CSMPL en el disco y proceso condilar. En mujeres, la media de inserción en el disco estuvo entre 5,7-5,5 mm (SD 1,5- 1,3) correspondiente al 69,8-70,7 por ciento de la CSMPL. En hombres, la media de inserción en el disco estuvo entre 6,2-6,12mm (SD 1,8-1,9) correspondiente al 68,9-74,2 por ciento de la CSMPL. No hubo diferencias en cuanto al sexo de los pacientes o lado de la articulación. Hemos encontrado un porcentaje significativo de las fibras de la CSMPL insertadas en el disco de ATMs asintomáticas, y su papel en el desplazamiento anterior del disco y el desarrollo de disfunción temporomandibular debe ser revisado.

Effects of detachment and repositioning of the medial pterygoid muscle on the growth of the maxilla and mandible of young rats / Efeitos do descolamento e do reposicionamento do músculo pterigoideo medial no crescimento da maxila e da mandíbula em ratos jovens

PURPOSE: To analyze the effects of detachment and repositioning of the medial pterygoid muscle on the growth of the maxilla and mandible of young rats through cephalometry. METHODS: Thirty one-month-old Wistar rats were used, distributed into three groups: experimental, sham-operated and control. In the experimental group, unilateral detachment and repositioning of the medial pterygoid muscle was performed. The sham-operated group only underwent surgical access, and the control group did not undergo any procedure. The animals were sacrificed at the age of three months. Their soft tissues were removed and the mandible was disarticulated. Radiographs of the skull in axial projection and the hemimandibles in lateral projection were obtained, and cephalometry was performed. The values obtained were subjected to statistical analyses among the groups and between the sides in each group. RESULTS: There were significant differences in the length of the mandible relative to the angular process in the experimental group and in the height of the mandibular body in the sham-operated group. CONCLUSION: The experimental detachment and repositioning of the medial pterygoid muscle during the growth period in rats affected the growth of the angle region, resulting in asymmetry of the mandible.

OBJETIVO: Avaliar os efeitos do descolamento e reposicionamento do músculo pterigoideo medial no crescimento da maxila e mandíbula em ratos jovens por meio de cefalometria. MÉTODOS: Foram utilizados 30 ratos Wistar com um mês de idade, distribuídos em três grupos: experimental, controle-operado e controle. No grupo experimental, o descolamento unilateral e reposicionamento do músculo pterigoideo medial foi realizado. O grupo controle-operado foi submetido somente ao acesso cirúrgico e para o grupo controle nenhum procedimento foi realizado. Os animais foram sacrificados aos três meses de idade. Os tecidos moles foram removidos e a mandíbula foi desarticulada. Radiografias axiais do crânio e laterais das hemimandíbulas foram obtidas e a cefalometria foi realizada. Os valores obtidos foram submetidos a análises estatísticas entre os grupos e entre os lados em cada grupo. RESULTADOS: Houve diferenças significantes no comprimento da mandíbula relativo ao processo angular no grupo experimental e na altura do corpo mandibular no grupo controle operado. CONCLUSÃO: O descolamento e reposicionamento experimental do músculo pterigoideo medial durante o período de crescimento em ratos comprometeu o crescimento na região de ângulo, resultando em assimetria da mandíbula.