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Posterior interosseous nerve syndrome is the most frequent syndrome of radial nerve compression, with the arcade of Frohse being the main site of compression. Its symptoms include difficulties in finger and wrist extension with possible radial deviation. Herein, we present a case of posterior interosseous syndrome caused by a schwannoma, a type of neurological tumor.

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OBJECTIVE: To detail the neurovascular crossing patterns between the leash of Henry (LoH) and the deep branch of the radial nerve (DBRN) in supination and pronation of the forearm, using imaging methods with anatomic correlation. MATERIALS AND METHODS: This cross-sectional study was performed ex vivo with HRUS and MRI with anatomic correlation on 6 samples and in vivo with HRUS with Doppler on 55 participants scanned bilaterally. The in vivo participants were enrolled over a 6-month period. The crossing patterns between the LoH and DBRN were assessed ex vivo and in vivo. Additional morphological features of the DBRN, LoH, and fat plane were assessed in vivo only. Biometric features of the participants were recorded. Statistical analyses were performed using Shapiro-Wilk, parametric and non-parametric tests. RESULTS: The most common neurovascular crossing pattern was the ascending branch of the radial recurrent artery (RRAab) crossing below (ex vivo: 83.3%, in vivo: 85.3%) and the muscular branch crossing above (ex vivo: 100%, in vivo: 63.2% %) the DBRN. Both the deep and superficial surfaces of the DBRN exhibited an intimate relationship with the vessels of the LoH. A positive correlation between vessel diameter and anthropometric factors was observed. In addition, the muscular branch exhibited a significantly smaller diameter than the RRAab. CONCLUSION: Our study detailed the relationship between the LoH and the DBRN and highlighted the high incidence of vessel crossing above the DBRN at the level of the muscular branch. Knowledge of neurovascular crossings is crucial for understanding neurovascular entrapment syndromes and planning interventional procedures to reduce vascular complications.

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PURPOSE: This study shows the danger zone and the safety corridor in the lateral approach with bridge plating by measuring the distance between the lateral side of the plate positioned on the lateral aspect of the humerus and the radial nerve after it pierces the lateral intermuscular septum, in the different forearm positions. METHODS: Forty arms of 20 human cadavers were used, the radial nerve was identified and marked on the lateral surface the radial nerve at the exit of the lateral intermuscular septum and anteriorisation of the nerve in relation to the humeral shaft and the lateral epicondyle was also marked. The distances were measured with a digital caliper. A submuscular extraperiosteal corridor was created, proximally between the biceps brachialis and deltoid muscle and distally between the triceps and brachioradialis muscle, followed by the positioning of the low contact large fragments contoured plate with 14 combined holes (fixed and cortical angle), inserted from distal to proximal. Measurements were performed in four positions (elbow flexion with forearm pronation, elbow flexion with forearm supination, elbow extension with forearm pronation and elbow extension with forearm supination). RESULTS: Significant statistical differences occurred with the different positions, and the elbow flexion with forearm supination was shown to be the position that provides the safest submuscular extraperiosteal corridor in a lateral approach of the humerus. CONCLUSION: The danger zone of radial nerve is an area that extends from 15 cm to 5 cm proximal to the lateral epicondyle and the safest way to create a submuscular and extraperiosteal corridor in the lateral region of the humerus is with the elbow in flexion and the forearm in supination.

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Background: Open reduction and internal fixation with plate is one of the most widely used treatments for distal third humeral shaft fractures. The purpose of this study was to report the outcomes of the treatment of distal third humeral shaft fractures with posterior minimally invasive plate osteosynthesis (MIPO) with segmental isolation of the radial nerve. Methods: We performed an observational, retrospective, consecutive, monocentric, continuous multioperator study. We reviewed 22 distal third humeral shaft fractures treated with posterior MIPO in our institution with an extra-articular distal humerus plate from 2018 to 2021. Inclusion was limited to functionally independent patients with displaced fractures involving the junction of the middle and distal thirds of the humerus and minimum 12-month follow-up for implant removal. We assessed clinical outcomes including range of motion; QuickDASH score; Mayo Elbow Performance Score; and Constant-Murley score. Results: The average follow-up period of the sample was 31.7 ± 11.6 months (range, 15.7-51.3 months). The average elbow flexion and extension were 146.4° ± 7.3° (range, 120°-150°) and -0.7° ± 3.3° (range, -15° to 0°), respectively. The average shoulder anterior flexion, elevation, and abduction were 178.6° ± 3.6° (range, 170°-180°), 179.1° ± 2.9° (range, 170°-180°), and 140.9° ± 14.8° (range, 110°-160°), respectively. The average external rotation was 88.6° ± 6.4 (range, 65°-90°). The mean visual analog scale score for pain was 1.0 ± 1.6 (range, 0-5) and the mean Mayo Elbow Performance Score was 90.5 ± 9.9 (range, 70-100). The mean QuickDASH and Constant-Murley scores were 4.7 ± 6.8 (range, 0-20.5) and 95.5 ± 5.1 (range, 81-100), respectively. Two patients presented with relevant compromise of radial nerve motor function postoperatively (M3 and M2; the more compromised was preoperative injury). All patients recovered radial nerve neuropraxia within six weeks postoperatively. All fractures achieved union. The average anteroposterior and lateral axis were 175.0 ± 3.6 (168.0°-180.0°) and 177.5 ± 2.0 (173.0°-180.0°), respectively. No superficial or deep infection was reported. No cases of re-displacement of fracture, implant failure, or any other implant-related complication in follow-up were reported. No patient required plate withdrawal. Conclusion: The results of this study demonstrate that the posterior MIPO technique is a reliable option for treating distal third shaft humeral fractures. The radial nerve must be identified and protected in all cases to prevent palsy.

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SUMMARY: Variations in the triceps brachii muscle are uncommon, and especially limited reports exist on the accessory heads of tendinous origin that attach near the upper medial part of the humerus. During anatomical training at Nagasaki University School of Medicine, the accessory head of the triceps brachii muscle was observed on the right upper arm of a 72-year-old Japanese female. It arose tendinously from the medial side of the upper humerus, then formed a muscle belly and joined the distal side of the long head. This accessory head had independent nerve innervation, and the innervating nerve branched from a bundle of the radial nerve, which divided the nerve innervating the long head and the posterior brachial cutaneous nerve. The origin of the innervation of the accessory head was the basis for determining that this muscle head was an accessory muscle to the long head of the triceps brachii muscle. Embryologically, we discuss that part of the origin of the long head of the triceps brachii muscle was separated early in development by the axillary nerve and the posterior brachial circumflex artery, and it slipped into the surgical neck of the humerus and became fixed there. The accessory head crossed the radial nerve and deep brachial artery. When clinicians encounter compression of the radial nerve or profunda brachii artery, they should consider the presence of accessory muscles as a possible cause.

Las variaciones en el músculo tríceps braquial son poco comunes y existen informes especialmente limitados sobre las cabezas accesorias de origen tendinoso que se insertan cerca de la parte medial superior del húmero. Durante un entrenamiento anatómico en la Facultad de Medicina de la Universidad de Nagasaki, se observó la cabeza accesoria del músculo tríceps braquial en la parte superior del brazo derecho de una mujer japonesa de 72 años. Se originaba tendinosamente desde el lado medial de la parte superior del húmero, luego formaba un vientre muscular y se unía al lado distal de la cabeza larga. Esta cabeza accesoria tenía inervación nerviosa independiente, cuyo nervio se ramificaba a partir de un ramo del nervio radial, que dividía el nervio que inervaba la cabeza larga y el nervio cutáneo braquial posterior. El origen de la inervación de la cabeza accesoria fue la base para determinar que esta cabeza muscular era un músculo accesorio de la cabeza larga del músculo tríceps braquial. Embriológicamente, discutimos que parte del origen de la cabeza larga del músculo tríceps braquial se separó temprananamente en el desarrollo por el nervio axilar y la arteria circunfleja braquial posterior, y se deslizó hacia el cuello quirúrgico del húmero y quedó fijado allí. La cabeza accesoria cruzaba el nervio radial y la arteria braquial profunda. Cuando los médicos encuentran compresión del nervio radial o de la arteria braquial profunda, deben considerar la presencia de mús- culos accesorios como una posible causa.

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Abstract Posterior interosseous nerve syndrome is the most frequent syndrome of radial nerve compression, with the arcade of Frohse being the main site of compression. Its symptoms include difficulties in finger and wrist extension with possible radial deviation. Herein, we present a case of posterior interosseous syndrome caused by a schwannoma, a type of neurological tumor.

Resumo A síndrome interóssea posterior é a síndrome mais frequente de compressão do nervo radial, com a arcada de Frohse sendo o principal local de compressão. Seus sintomas incluem dificuldades na extensão do dedo e punho, com possível desvio radial. Aqui, apresentamos um caso de síndrome interóssea posterior causada por um schwannoma, um tipo de tumor neurológico.

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Resumen Objetivo: Analizar los resultados de la técnica quirúrgica de colocación de clavillos Kirschner forma lateral versus cruzada en el manejo de las fracturas supracondíleas de húmero en pacientes pediátricos. Metodología: Se captaron a todos los pacientes con fractura supracondílea humeral en edad pediátrica que requirieron intervención quirúrgica, y posteriormente fueron evaluados a las 24 horas y 6 meses posterior al tratamiento quirúrgico para observar y comparar las diferencias entre cada técnica quirúrgica utilizada, tomando en cuenta las complicaciones agudas y tardías que se presentaron mediante un análisis con la prueba de Mann-Whitney. Resultados: Para el presente estudios se evaluaron 44 pacientes pediátricos de los cuales 70% eran hombres y 30% mujeres, en quienes se presentaron complicaciones nerviosas y angulares sin importancia significativa alguna con el sexo y edades de los pacientes, siendo la afección del nervio cubital la de mayor frecuencia con 33% en la colocación de forma cruzada. Al realizar la comparativa con discriminación de variables se obtiene que la colocación de forma lateral presenta menos complicaciones posquirúrgicas tempranas y tardías y que tales no se deben al azar. Limitaciones o implicaciones: En el presente estudio no se incluyó el tipo de daño mecánico que provoca este tipo de fractura, ni se consideró el ángulo de Baumann. Otra limitación inherente en la población pediátrica es la habilidad del explorador para detectar un déficit neurológico, especialmente en pacientes de edad temprana dado a que los reportes de una exploración física siempre son subjetivos. Además, dada la limitación en cuanto a los detalles del mecanismo específico de daño, se puede subestimar el número de daños provocados por mecanismos de alta energía. Originalidad y valor: Su importancia radica en que ambas técnicas quirúrgicas fueron realizadas por los mismos cirujanos y que se trata de un estudio en población mexicana, siendo un aporte para la literatura de este país. Conclusión: Ambas técnicas quirúrgicas presentan resultados posquirúrgicos con casos de lesión nerviosa, deformidad angular, dolor y edema persistente, pero la que los presenta en menor frecuencia es la técnica de colocación de clavillos Kirschner en forma lateral, además de causar una significancia estadística en cuanto a la disminución de presentar cubito valgo en el seguimiento tardío de los pacientes.

Abstract: Objective: To analyze the results of the surgical technique placement of Kirschner pins lateral versus crossed in the management of supracondylar fractures of the humerus in pediatric patients. Methodology: All pediatric patients with humeral supracondylar fracture who required surgical intervention and were subsequently evaluated 24 hours and 6 months after surgical treatment to observe and compare the differences between each patient. surgical technique used. Taking into account the acute and late complications that occurred, through an analysis with the Mann-Whitney test. Results: For the present studies, 44 pediatric patients were evaluated, of whom 70% were men and 30% women, in whom nerve and angular complications presented without any significant importance with the sex and age of the patients, with ulnar nerve involvement being the most frequent with 33% in cross placement. When carrying out the comparison with discrimination of variables, it is obtained that the placement laterally presents fewer early and late post-surgical complications and that such are not due to chance. Or the present study, it is considered that a placement of Kirschner pins laterally regardless of the member, age, gender or classification; leads to better post-surgical results. Limitations or implications: In the present study, the type of mechanical damage that causes this type of fracture was not included, nor was the Baumann angle considered. Another limitation inherent in the pediatric population is the ability of the examiner to detect a neurological deficit, especially in young patients since reports of a physical examination are always subjective. Furthermore, given the limited details of the specific damage mechanism, the number of damages caused by high-energy mechanisms may be underestimated. Originality or value: Its importance lies in the fact that both surgical techniques were performed by the same surgeons and that it is a study in the mexican population, being a contribution to the literature of this country. Findings or conclusions: Both surgical techniques present post-surgical results with cases of nerve injury, angular deformity, pain and persistent edema, but the one that presents them less frequently in the technique of placement of Kirschner pins laterally, in addition to causing statistical significance in terms of the decrease of presenting cubitus valgus in the late follow-up of the patients.

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OBJECTIVE: To evaluate the effect of maximal pronation and supination of the forearm on the alignment and anatomic relationship of the deep branch of the radial nerve (DBRN) at the superior arcade of the supinator muscle (SASM) by using high-resolution ultrasound (HRUS). MATERIALS AND METHODS: In this cross-sectional study, HRUS in the long axis of the DBRN was performed in asymptomatic participants enrolled from March to August 2021. DBRN alignment was evaluated by measuring angles of the nerve in maximal pronation and maximal supination of the forearm independently by two musculoskeletal radiologists. Forearm range of motion and biometric measurements were recorded. Student t, Shapiro-Wilk, Pearson correlation, reliability analyses, and Kruskal-Wallis test were used. RESULTS: The study population included 110 nerves from 55 asymptomatic participants (median age, 37.0 years; age range, 16-63 years; 29 [52.7%] women). There was a statistically significant difference between the DBRN angle in maximal supination and maximal pronation (Reader 1: 95% CI: 5.74, 8.21, p < 0.001, and Reader 2: 95% CI: 5.82, 8.37, p < 0.001). The mean difference between the angles in maximal supination and maximal pronation was approximately 7° for both readers. ICC was very good for intraobserver agreement (Reader1: r ≥ 0.92, p < 0.001; Reader 2: r ≥ 0.93, p < 0.001), as well as for interobserver agreement (phase 1: r ≥ 0.87, p < 0.001; phase 2: r ≥ 0.90, p < 0.001). CONCLUSION: The extremes of the rotational movement of the forearm affect the longitudinal morphology and anatomic relationships of the DBRN, primarily demonstrating the convergence of the nerve towards the SASM in maximal pronation and divergence in maximal supination.

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SUMMARY: The axilla is the main communication channel connecting the upper limbs, the neck and chest. Stabilization of the internal structure is essential for upper limb and shoulder mobility. In this case, we observed and recorded the characteristics of the variation of the radial nerve as well as the intercalated ectopic muscle from latissimus dorsi muscle. The position relationship between both, was also particularly noted by us. In view of the presence of the variation we reported, related clinical research, surgery and disease diagnosis are expected to take this case into account.

La axila es el principal canal de comunicación que conecta los miembros superiores, el cuello y el tórax. La estabilización de la estructura interna es fundamental para la movilidad del miembro superior y del hombro. En este caso observamos y registramos las características de la variación del nervio radial así como del músculo ectópico intercalado del músculo latísimo del dorso. La relación de posición entre ambas también fue significativa en este estudio. En vista de la presencia de la variación que informamos, se espera que la investigación clínica relacionada con la cirugía y el diagnóstico de la enfermedad tengan en cuenta este caso.

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SUMMARY: The deep branch of the radial nerve (DBRN) runs through the radial tunnel, which is a muscle-aponeurotic structure that extends from the humeral lateral epicondyle to the distal margin of the supinator muscle (SM). The Posterior Interosseous Nerve (PIN) originates as a direct continuation of the DBRN as it emerges from the SM and supplies most of the muscles of the posterior compartment of the forearm. The PIN can be affected by compressive neuropathies, especially at the "Arcade of Frohse". Its preservation is of special interest in surgical approaches to proximal radius fractures and in compressive syndromes release, for which surgeons must have an adequate anatomical knowledge of its course. This descriptive cross-sectional study evaluated 40 upper limbs of fresh cadavers. The diameters of the DBRN, the length of the radial tunnel, and the distances to the supinator arch, PIN emergence and PIN bifurcation were measured. The deep branch of the radial nerve (DBRN) has a course of 23.8 ± 3.7 mm from its origin to the supinator arch, presenting a diameter of 2.2 ± 0.3 mm at that level. The length of the radial tunnel was 42.2 ± 4 mm. The PIN originated 70.7 ± 3.5 mm distal to the lateral epicondyle. Type I corresponds to the division of the PIN during its journey through the radial tunnel, presenting in 35 % of cases, and Type II corresponds to the division of the PIN distal to its emergence from the radial tunnel presenting in the remaining 65 %. This study enriches the knowledge of the PIN and provides useful reference information on a Latin American mestizo sample. We propose the division pattern of the PIN into two types. Future studies may use this classification not only as a qualitative variable, but also include quantitative morphometric measurements.

El ramo profundo del nervio radial (RPNR) discurre por el túnel radial, que es una estructura músculo- aponeurótica que se extiende desde el epicóndilo lateral del húmero humeral hasta el margen distal del músculo supinador (MS). El nervio interóseo Posterior (NIP) se origina como una continuación directa del RPNR cuando emerge del MS e inerva la mayoría de los músculos del compartimiento posterior del antebrazo. El NIP puede verse afectado por neuropatías compresivas, especialmente en la "Arcada de Frohse". Su conservación es de especial interés en los abordajes quirúrgicos de las fracturas proximales de radio y en la liberación de síndromes compresivos, para lo cual los cirujanos deben tener un adecuado conocimiento anatómico de su curso. Este estudio descriptivo transversal evaluó 40 miembros superiores de cadáveres frescos. Se midieron los diámetros de la RPNR, la longitud del túnel radial y las distancias al arco supinador, la emergencia del NIP y la bifurcación del NIP. El RPNR tenía un recorrido de 23,8 ± 3,7 mm desde su origen hasta el arco supinador, presentando un diámetro de 2,2 ± 0,3 mm a ese nivel. La longitud del túnel radial fue de 42,2 ± 4 mm. El NIP se originó 70,7 ± 3,5 mm distal al epicóndilo lateral. El tipo I corresponde a la división del NIP durante su recorrido por el túnel radial presentándose en el 35 % de los casos, y el tipo II corresponde a la división del NIP distal a su salida del túnel radial presentándose en el 65 % restante. Este estudio enriquece el conocimiento del NIP y proporciona información de referencia útil sobre una muestra de mestizos latinoamericanos. Proponemos el patrón de división del NIP en dos tipos. Futuros estudios pueden utilizar esta clasificación no solo como una variable cualitativa, sino también incluir medidas morfométricas cuantitativas.

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This laboratory cross-sectional study aimed at explore the muscle response (MR) of the upper trapezius, infraspinatus, biceps brachii and extensor carpi radialis brevis (ECRB) during the radial nerve-biased upper limb neurodynamic test (RN-ULNT) in healthy participants. Myoelectric activity was stage-by-stage recorded during two sequencing variants of the RN-ULNT: S1, in which elbow extension was the last movement; and S2, in which wrist flexion was the last movement. Final elbow and wrist joint angle and sensory response (SR) in five zones (Z1-Z5) were also registered. MR was qualitatively categorized as 'absent' (No-MR), 'true' (TMR) or 'uneven' (UMR). In both sequences, significant increases in muscle activity occurred mostly during shoulder abduction and elbow extension (p ≤ 0.009). Also, elbow extension but not wrist flexion increased the activity of the ECRB muscle (p ≤ 0.009). S2 showed significantly higher upper trapezius (p = 0.04) and biceps brachii (p = 0.036) muscle activity during wrist flexion, and higher report of SR in Z1 and Z4 (p < 0.001) compared to S1. Only the ECRB muscle showed significant differences in the MR type between S1 and S2 (TMR, p = 0.016; UMR, = 0,012). Our results may be useful in the assessment of upper limb musculoskeletal disorders.

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Radial glia is a cell type traditionally associated with the developing nervous system, particularly with the formation of cortical layers in the mammalian brain. Nonetheless, some of these cells, or closely related types, called radial glia-like cells are found in adult central nervous system structures, functioning as neurogenic progenitors in normal homeostatic maintenance and in response to injury. The heterogeneity of radial glia-like cells is nowadays being probed with molecular tools, primarily by the expression of specific genes that define cell types. Similar markers have identified radial glia-like cells in the nervous system of non-vertebrate organisms. In this review, we focus on adult radial glia-like cells in neurogenic processes during homeostasis and in response to injury. We highlight our results using a non-vertebrate model system, the echinoderm Holothuria glaberrima where we have described a radial glia-like cell that plays a prominent role in the regeneration of the holothurian central nervous system.

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Background: Safety zones to avoid nerve injury at proximal incision of posterior minimally invasive plate osteosynthesis for humerus fracture have been scarcely studied. The purpose of this study was to describe the location of axillary and radial nerves (RN) in magnetic resonance imaging to establish safety zones. Methods: Fifty-two magnetic resonance imaging studies of the entire humerus were reviewed. The mean age was 50.6 ± 12.1 years, with 37 female patients. The distance of the axillary nerve (AN; distal portion, humeral midpoint) and RN (medial border, midpoint, and lateral border of the humerus) was measured in relation to the posterolateral acromion angle, acromioclavicular axis, and transepicondylar axis. Univariate analysis (Student's t test) and a multivariate analysis (linear regression) were performed. P values < .05 were considered significant. Results: The AN location at the humerus was 54.9 ± 6.4 mm (20.1% humeral length [HL]) in relation to posterolateral acromion angle and 63.2 ± 6.1 mm (23.2% HL) in relation to acromioclavicular axis. The RN location was 100.2 ± 17.1 mm (36.6% HL) at the humerus medial border, 118.0 ± 21.5 mm (43.1% HL) at the humerus midpoint, and 146.0 ± 24.4 mm (53.6% HL) at the humerus lateral border. In relation to transepicondylar axis, it was 175.4 ± 15.6 mm (64.3% HL), 156.0 ± 19.0 mm (57.2% HL), and 127.4 ± 21.2 mm (46.7% HL), respectively. Nerves location was related to HL, independent of gender. Conclusion: The main finding of our study is that the location of the AN and RN in relation to the humerus is related to the HL and can be used to predictably define the safe zones to avoid nerve injury in the proximal incision of posterior minimally invasive plate osteosynthesis for humerus fractures.

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Benign tumors of peripheral nerves called Schwannomas or neurilemomas, correspond to a rare pathology, represent 5% of all tumors of the upper extremity, and affects, mainly, the ulnar nerve. The incidence of Schwannoma in the literature for the radial nerve is not clearly established given the infrequency of its presentation, there are only reports of isolated cases The following publication presents the case of a male patient with a radial nerve schwannoma. Clinically, presents increased painful volume on palpation, well delimited, of soft consistency in the distal third of the right arm of 3 years of evolution, without history of previous trauma, without irradiation, or paresthesia, with preservation of motor and sensory function of radial, median and ulnar nerve. Considering that the involvement of the radial nerve is very low frequency, a review is carried out in PubMed, in the last 10 years, there are only 9 studies, grouped in case reports and imaging studies for diagnosis.

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La parálisis radial neonatal aislada (PRNA) es un cuadro clínico infrecuente que debe distinguirse de otras entidades más frecuentes, como la parálisis braquial obstétrica (PBO). Debemos sospechar una PRNA en neonatos que presentan incapacidad para la extensión de muñeca y de dedos, pero mantienen intacta la función del deltoides, del bíceps, y del tríceps, así como la flexión de muñeca y de dedos. Mientras la PBO tiene una evolución clínica variable dependiendo de la extensión de la lesión neurológica, la PRNA presenta una resolución espontánea, independientemente del grado de afectación inicial. Presentamos el caso de un recién nacido con PRNA cuyo diagnóstico inicial fue de PBO.

Isolated radial nerve palsy (IRNP) in the newborn is a rare clinical condition that must be distinguished from entities that are more common, such brachial plexus birth palsy (BPBP). It should be suspected in newborns presenting with absent wrist and digital extension but intact deltoid, biceps, and triceps function, as well as wrist and digital flexor function. Whereas BPBP is highly variable depending on the extent of the neurological involvement, IRNP resolves spontaneously, regardless of the severity of the initial presentation. We herein present a case of newborn with IRNP whose initial diagnosis was of BPBP.

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OBJECTIVE: The authors sought to describe the anatomy of the radial nerve and its branches when exposed through an axillary anterior arm approach. METHODS: Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery. RESULTS: Via the anterior arm approach, all triceps muscle heads could be dissected and individualized. The radial nerve overlaid the latissimus dorsi tendon, bounded by the axillar artery on its superior surface, then passed around the humerus, together with the lower lateral arm and posterior antebrachial cutaneous nerve, between the lateral and medial heads of the triceps. No triceps motor branch accompanied the radial nerve's trajectory. Over the latissimus dorsi tendon, an antero-inferior bundle, containing all radial nerve branches to the triceps, was consistently observed. In the majority of the dissections, a single branch to the long head and dual innervations for the lateral and medial heads were observed. The triceps long and proximal lateral head branches entered the triceps muscle close to the latissimus dorsi tendon. The second branch to the lateral head stemmed from the triceps lower head motor branch. The triceps medial head was innervated by the upper medial head motor branch, which followed the ulnar nerve to enter the medial head on its anterior surface. The distal branch to the triceps medial head also originated near the distal border of the latissimus dorsi tendon. After a short trajectory, a branch went out that penetrated the medial head on its posterior surface. The triceps lower medial head motor branch ended in the anconeus muscle, after traveling inside the triceps medial head. The lower lateral arm and posterior antebrachial cutaneous nerve followed the radial nerve within the torsion canal. The lower lateral brachial cutaneous nerve innervated the skin over the biceps, while the posterior antebrachial cutaneous nerve innervated the skin over the lateral epicondyle and posterior surface of the forearm. The average numbers of myelinated fibers were 926 in the long and 439 in the upper lateral head and 658 in the upper and 1137 in the lower medial head motor branches. CONCLUSIONS: The new understanding of radial nerve anatomy delineated in this study should aid surgeons during reconstructive surgery to treat upper-limb paralysis.

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Objetivo Confirmar factibilidad técnica de la neurotización del nervio axilar por la rama motora de la porción larga del tríceps con el fin de definir la anatomía quirúrgica de los nervios radial y axilar. Materiales y métodos Veinte hombros de cadáver fueron intervenidos para transferencia de la rama del Nervio Radial para la porción larga del tríceps a la rama anterior del Nervio Axilar por abordaje axilar. Se confirmó la escogencia correcta del nervio receptor por abordaje posterior. Resultados Se logró una disección adecuada de la primera rama motora del nervio radial del nervio axilar y de la rama anterior del Nervio Axilar. El origen de la rama motora se encontró en promedio a 3,8mm (+/- 7,3mm) distal al borde superior del tendón del dorsal ancho. El nervio axilar se encontró cefálico al borde superior del dorsal ancho a una distancia promedio de 11,3mm (+/-2,13mm) y distal al redondo menor 3.05mm (+/- 1,3mm), sutura con la primera rama del radial en el 100% de los casos sin tensión y se confirmó la adecuada transferencia en todos los casos. Conclusión La neurotización del nervio axilar con la primera rama del nervio radial se logró con éxito en el 100% por vía axilar. Este abordaje es adecuado, evitando tener que realizar cambios de posición a prono y doble abordaje, y si se requiere procedimientos adicionales de reconstrucción en el mismo tiempo quirúrgico tipo Oberlin y exploraciones supraclaviculares del plexo braquial se pueden realizar sin cambio de posición.

Objective To confirm the technical feasibility of neurotization of the axillary nerve by the motor branch of the long head of the triceps in order to define the surgical anatomy of the radial and axillary nerves. Materials and method Twenty cadaver shoulders were operated on for transfer of the radial nerve branch for the long head of the triceps to the anterior branch of the axillary nerve by axillary approach. The correct choice of the receiving nerve was confirmed by posterior approach. Results An adequate dissection of the first motor branch of the radial nerve of the axillary nerve and of the anterior branch of the Axillary Nerve was achieved, The origin of the motor branch was found on average at 3.8mm (+/−7.3mm) distal to the superior border of the latissimus dorsi tendon. The axillary nerve was found 11.3mm (+/−2.13mm) cephalad to the upper border of the latissimus dorsi and 3.05mm (+/−1.3mm) distal to the teres minor. A tensionless coaptation was obtained in all cases. Conclusion Neurotization of the axillary nerve with the first branch of the radial nerve was successfully achieved through the axillary approach. This approach is adequate, avoiding position change to prone and double approach, and if additional reconstruction procedures are required at the same surgical time, Oberlin type and supraclavicular explorations of the brachial plexus can be performed without changing position.

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In recent decades, high-resolution ultrasound (HRUS) has revolutionized the morphological and structural evaluation of peripheral nerves and muscles, revealing details of the internal structure of the neural fascicles and muscle architecture. Applications range from diagnostics to interventional procedures. The anatomy of the forearm region is complex, with several muscles and an extensive network of vessels and nerves. To guarantee the success of the evaluation by HRUS, knowledge of the normal anatomy of the region is essential. The aim of these two companion articles is to present the normal anatomy of the nerves and compartments of the forearm, as revealed by HRUS, as well as the relationships between the main vessels and nerves of the region. Part 1 aims to review the overall structure of nerves, muscles and tendons, as seen on HRUS, and that of the forearm compartments. We present a practical approach, with general guidelines and tips on how best to perform the study. Part 2 is a pictorial essay about compartment vascularization and cutaneous innervation. Knowledge of the normal anatomy of the forearm improves the technical quality of the examinations, contributing to better diagnoses, as well as improving the performance and safety of interventional procedures.

RESUMO

Abstract In recent decades, high-resolution ultrasound (HRUS) has revolutionized the morphological and structural evaluation of peripheral nerves and muscles, revealing details of the internal structure of the neural fascicles and muscle architecture. Applications range from diagnostics to interventional procedures. The anatomy of the forearm region is complex, with several muscles and an extensive network of vessels and nerves. To guarantee the success of the evaluation by HRUS, knowledge of the normal anatomy of the region is essential. The aim of these two companion articles is to present the normal anatomy of the nerves and compartments of the forearm, as revealed by HRUS, as well as the relationships between the main vessels and nerves of the region. Part 1 aims to review the overall structure of nerves, muscles and tendons, as seen on HRUS, and that of the forearm compartments. We present a practical approach, with general guidelines and tips on how best to perform the study. Part 2 is a pictorial essay about compartment vascularization and cutaneous innervation. Knowledge of the normal anatomy of the forearm improves the technical quality of the examinations, contributing to better diagnoses, as well as improving the performance and safety of interventional procedures.

RESUMO

RESUMEN: El nervio interóseo posterior (NIP) ha sido utilizado como sinónimo ocontinuación inmediata del ramo profundo del nervio radial (RPNR) al emerger en el compartimiento posterior del antebrazo. Su origen tampoco es claro, describiéndose como nervio interóseo posterior a su trayecto proximal, intermedio o distal al músculo supinador. El objetivo de esta revisión es detallar la visión de diversos autores respecto al origen y trayecto del NIP, proponiendo una correcta terminología para estas estructuras. Se realizó una revisión bibliográfica de varios textos y de algunos artículos utilizados para la enseñanza de la anatomía humana, publicados entre los años 1800 y la actualidad. En la búsqueda, se determinaron criterios de inclusión que consideraban, anatomía humana, escritos en español, francés o inglés y que aludieran al NIP. Tras la exploración inicial se localizaron 18 libros, procedentes de Francia, Rusia, España, Argentina, Estados Unidos, Canadá, Reino Unido, Alemania, India y México. Una descripción del NIP más precisa, en cuanto al origen, trayecto y función, es aquella postulada por la vertiente francesa, correspondiendo a un origen terminal del ramo profundo del nervio radial, luego de emitir sus ramos musculares. Este delgado nervio transcurre adosado a la membrana interósea para luego avanzar por el cuarto compartimiento extensor, distribuyéndose en las articulaciones dorsales del carpo a quienes inerva sensitiva y propioceptivamente.

SUMMARY: The posterior interosseous nerve (PIN) has been used as a synonym or immediate continuation of the deep branch of the radial nerve as it emerges in the posterior compartment of the forearm. Its origin is not clear either, being described as a posterior interosseous nerve to its proximal, intermediate or distal path to the supinator muscle. The objective of this review is to detail the vision of various authors regarding the origin and path of the PIN, proposing a correct terminology for these structures. A bibliographic review of several texts and some articles used for the teaching of human anatomy, published between the 1800s and the present day, was carried out. In the search, inclusion criteria were determined that considered human anatomy, written in Spanish, French or English and that alluded to the PIN. After the initial exploration, 18 books were located, coming from France, Russia, Spain, Argentina, the United States, Canada, the United Kingdom, Germany, India and Mexico. A more precise description of the PIN, in terms of origin, path and function, is that postulated by the French literature, corresponding to a terminal origin of the deep branch of the radial nerve, after emitting its muscular branches. This thin nerve runs attached to the interosseous membrane to then advance through the fourth extensor compartment, distributing itself in the dorsal carpal joints to which it innervates sensitively and proprioceptively.

Assuntos