Comparison of two volumes for sciatic perineural injection using 1% methylene blue in rabbit cadavers / [Comparação de dois volumes para injeção perineural no nervo isquiático utilizando azul de metileno 1% em cadáveres de coelhos]

The purpose of this study was to assess the efficacy of a blind technique for sciatic and femoral nerve block in rabbit cadavers by evaluating the spread of 1% methylene blue at two different volumes. Nine recently euthanized rabbits weighing 2.5(0.3kg were used. The sciatic (SN) and femoral (FN) nerves of each limb were randomly assigned for injection with 1% methylene blue at 0.2mL/kg (G0.2) or 0.3mL/kg (G0.3). Nerves were dissected and measured for depth and extension of staining (cm). Mean comparisons were performed using paired t test. The relation between volume and nerve staining ( 2cm was assessed using chi-square test. The mean depth of SN was 1.9±0.2 and 1.6±0.3cm and staining 1.9±1.4 and 2.0±1.2cm, respectively in G0.2 and G0.3. No relation was found between depth and dye spread and there was no association between nerve staining ( 2.0cm and volume of solution. The FN failed to be stained in all subjects. In conclusion, SN injection can be successfully performed without guidance in rabbits. The lower volume (0.2mL/kg) is recommended to avoid systemic toxicity.(AU)

O objetivo deste estudo foi avaliar a eficácia de uma técnica para bloqueio às cegas dos nervos isquiático e femoral em cadáveres de coelhos, por meio da avaliação da dispersão de azul de metileno 1% em dois volumes distintos. Nove coelhos recém-eutanasiados, com peso 2,5(0,3kg, foram utilizados. Os nervos isquiático (NI) e femoral (NF) de cada membro foram aleatoriamente designados para injeção com azul de metileno 1% a 0,2mL/kg (G0,2) ou 0,3mL/kg (G0,3). Em seguida, foram dissecados e mensurados em relação à sua profundidade e extensão corada (cm). As médias foram comparadas por meio de teste t pareado. A relação entre volume e extensão corada ( 2cm foi avaliada utilizando-se teste de qui-quadrado. A profundidade média do NI foi 1,9±0,2 e 1,6±0,3cm, e a extensão corada 1,9±1,4 e 2,0±1,2cm, respectivamente, no G0,2 e no G0,3. Não houve relação entre a profundidade e a extensão corada ou entre a extensão corada ( 2,0cm e o volume de solução. Não foi observada coloração do NF em nenhum cadáver. Concluiu-se que a injeção do NI pode ser realizada com sucesso sem auxílio de tecnologias em coelhos. O menor volume (0,2mL/kg) é recomendado para evitar toxicidade sistêmica.(AU)

Stem cells in end-to-side neurorrhaphy: experimental study in rats

Purpose: To evaluate the influence of mesenchymal stem cells from adipose tissue in the end-to-side neurorrhaphy, focusing in the nerve regeneration and the muscle reinnervation in acute trauma. Methods: 140 animals were randomly divided in seven groups: control, denervated, end-to-side neurorrhaphy between distal stump of common peroneal nerve and tibial nerve (ESN), ESN wrapped in fascia, ESN wrapped in fascia and platelet gel, ESN wrapped in platelet gel, ESN wrapped in fascia and platelet gel within stem cells (without culture) removed from the adipose tissue. Mass measurements of the animal and of cranial tibial muscles, electromyography, walking track analysis tests and histological examinations of the nerves and muscles after 180 days was performed. Results: In the groups where the ESN was performed, the results were always better when compared to the denervated group, showing reinnervation in all ESN groups. The most sensitive methods were walking track and histological analysis. Only the group with stem cells showed values similar to the control group, as well as the functional indices of peroneal nerve and the number of nerve fibers in the peroneal nerve. Conclusions: Stem cells were effective in ESN according with the functional index of the peroneal nerve, evaluated by walking track analysis and the number of nerve fibers in the peroneal nerve.(AU)

Comparative study between standard and inside-out vein graft techniques on sciatic nerve repair of rats: muscular and functional analysis

Purpose: To compare the functional result of standart vein grafts and inside-out vein graft technique on sciatic nerve repair. Methods: We used 24 male Wistar rats divided into 4 groups: control group (CG), standard vein graft group (SVG), Inside-out vein graft group (IOVG) and denervated Group (DG). SVG, IOVG and DG underwent total section of the sciatic nerve, SVG and IOVG however underwent nerve repair surgery using a graft with normal jugular vein and inside-out jugular vein, respectively. Histological analysis of the soleus and Extensor Digitorum Longus (EDL), and Sciatic Functional Index were used to compare the results after 6 weeks. Results: Both grafts acted favorably in muscle recovery and improved functionality; They were similar in all parameters, however, in more points SVG achieved similar to the CG, in the other hand IOVG more times was similar to DG. Fact that makes the graft with normal vein the most viable option between the two options. Conclusion: Both types of grafts acted beneficially wherein the graft normal vein has proved to be the best option.(AU)

Inside-out and standard vein grafts associated with platelet-rich plasma (PRP) in sciatic nerve repair. A histomorphometric study

Purpose: To evaluated the tubulization technique with standard and inside-out vein, filled or not with platelet-rich plasma (PRP), in sciatic nerve repair. Methods: Seventy male Wistar rats were randomly divided into five groups: IOVNF (Inside-Out Vein with No Filling); IOVPRP (Inside-Out Vein filled with PRP); SVNF (Standard Vein with No Filling); SVPRP (Standard Vein filled with PRP); Sham (Control). The left external jugular vein was used as graft in a 10 mm nervous gap. Results: In the morphological analysis of all groups, myelinated nerve fibers with evident myelin sheath, neoformation of the epineurium and perineurium, organization of intraneural fascicles and blood vessels were observed. In the morphometry of the distal stump fibers, SVPRP group had the highest means regarding fiber diameter (3.63±0.42 m), axon diameter (2.37±0.31 m) and myelin sheath area (11.70±0.84 m2). IOVPRP group had the highest means regarding axon area (4.39±1.16 m2) and myelin sheath thickness (0.80±0.19 m). As for values of the fiber area, IOVNF group shows highest means (15.54±0.67 m2), but are still lower than the values of the Sham group. Conclusion: The graft filled with platelet-rich plasma, with use standard (SVPRP) or inside-out vein (IOVPRP), promoted the improvement in axonal regeneration on sciatic nerve injury.(AU)

End-to-side versus end-to-end neurorrhaphy at the peroneal nerve in rats

Purpose: To evaluate three different kinds of neurorrhaphy of the peroneal nerve. Methods: Eigthy rats were divided into 5 groups. Control: nerve had no intervention. End-to-end (EE): nerve was cut and elongated with a nerve graft with two end-to-end neurorrhaphies. End-to-side (ES): nerve was cut and sutured to the graft with at the lateral side of the nerve. Side-to-end (SE): the nerve was cut and sutured to the graft with end-to-end neurorrhaphy. Denervated: nerve was cut and both endings were buried into the muscle. The evaluation was done by walking track analysis, electrophysiology, body mass, cranial tibial muscle mass, nerve and muscle fibers morphometry. Results: The EE, ES and SE have the same potential of reinnervation. Conclusion: There is no functional or histological difference between these different types of neurorrhaphy.(AU)

Descrição anatômica do plexo braquial de Callithrix jacchus e Callithrix penicillata / Anatomic description of brachial plexus of Callithrix jacchus and Callithrix penicillata

Callithrix jacchus e Callithrix penicillata são primatas de pequeno porte cuja utilização como modelo anatômico tem se mostrado cada vez mais frequente, não somente pela praticidade no manuseio como facilidade no trato em criatório e sua taxa de reprodução. Este estudo teve como objetivo descrever os componentes dos plexos braquial em Callithrix jacchus e penicillata. Para tanto, três espécimes com aproximadamente 8 anos e 240 g foram fixados em solução de formaldeído a 10%, e posteriormente dissecados e fotodocumentados. O plexo braquial do Callithrix jacchus e penicillata originou-se dos nervos espinhais C5 a T1 constituindo os troncos cranial, médio e caudal. A composição do plexo braquial destes animais se assemelha ao de outros primatas, bem como a outros mamíferos.(AU)

Callithrix jacchus and Callithrix penicillata are small primates used as anatomic model, not only for convenience in handling as ease in regard to breeding and reproductive rate. The aim of this study was to describe the components of the brachial plexus in Callithrix jacchus and C. penicillata. Three specimens about 8 years old and weighing 240g were fixed in 10% formaldehyde and subsequently dissected and photodocumented. The brachial plexus of Callithrix jacchus and C. penicillata originates from the spinal nerves C5 to T1 in continuation of the cranial, medium and flow trunk. The composition of the brachial plexus of these animals is similar to the one of other primates ands other mammals.(AU)

Descrição anatômica do plexo braquial de Callithrix jacchus e Callithrix penicillata / Anatomic description of brachial plexus of Callithrix jacchus and Callithrix penicillata

Callithrix jacchus and Callithrix penicillata are small primates used as anatomic model, not only for convenience in handling as ease in regard to breeding and reproductive rate. The aim of this study was to describe the components of the brachial plexus in Callithrix jacchus and C. penicillata. Three specimens about 8 years old and weighing 240g were fixed in 10% formaldehyde and subsequently dissected and photodocumented. The brachial plexus of Callithrix jacchus and C. penicillata originates from the spinal nerves C5 to T1 in continuation of the cranial, medium and flow trunk. The composition of the brachial plexus of these animals is similar to the one of other primates ands other mammals.(AU)

Callithrix jacchus e Callithrix penicillata são primatas de pequeno porte cuja utilização como modelo anatômico tem se mostrado cada vez mais frequente, não somente pela praticidade no manuseio como facilidade no trato em criatório e sua taxa de reprodução. Este estudo teve como objetivo descrever os componentes dos plexos braquial em Callithrix jacchus e penicillata. Para tanto, três espécimes com aproximadamente 8 anos e 240 g foram fixados em solução de formaldeído a 10%, e posteriormente dissecados e fotodocumentados. O plexo braquial do Callithrix jacchus e penicillata originou-se dos nervos espinhais C5 a T1 constituindo os troncos cranial, médio e caudal. A composição do plexo braquial destes animais se assemelha ao de outros primatas, bem como a outros mamíferos.(AU)

Combined polyglycolic acid tube and autografting versus autografting or polyglycolic acid tube alone. A comparative study of peripheral nerve regeneration in rats

PURPOSE: To compare sciatic nerve regeneration in rats using three different techniques of repair. METHODS: Fifteen isogonics rats were divided into three groups according to the method used to repair a 5-mm long defect created in the sciatic nerve: autogenous graft (Group A), polyglycolic acid tube (PGAt) (Group B), and of the association of PGAt with the graft (Group C). Histological analysis, regenerated myelinated axon number count and functional analysis were used to compare after six weeks. RESULTS: There was no difference in fiber diameter and degree of myelinization presented by Groups A, B and C. Group B presented the lowest number of regenerated axons. The groups did not display any significant functional difference after walking track analysis (p<0.05). CONCLUSION: No differences between the three groups in terms of functional recovery, although there were histological differences among them.(AU)

Peroneal nerve reconstruction by using glycerol-preserved veins: histological and functional assessment in rats

PURPOSE: To compare the degree of neural regeneration in rats upon interposition of autologous nerve graft, autogenous vein, glycerol-preserved autogenous vein, and glycerol-preserved allogeneic vein using qualitative and quantitative histological analyses as well as functional assessments. METHODS: Peroneal nerves were reconstructed differently in four groups of animals. Functional assessments were performed pre- and postoperatively for a period of six weeks. After six weeks, the animals were sacrificed and histological evaluations were performed. RESULTS: Histological patterns of autogenous veins without preservation showed pronounced neoangiogenesis and extensive axonal rarefaction, as confirmed by axonal counting and functional assessments. Glycerol-preserved veins had results similar to the control. CONCLUSIONS: Glycerol-preserved autogenous or allogeneic veins showed similar results to autograft results. The autogenous vein (without preservation in glycerol) presented histological and functional outcomes statistically lower than other groups.(AU)

Imagens ultrassonográficas do plexo braquial pela via axilar em cães

O uso da ultrassonografia na anestesia regional teve um crescimento vertiginoso nos últimos anos, devido ao grande progresso na resolução das imagens ultrassonográficas, permitindo a visibilização não só de vasos, mas de raízes nervosas e nervos periféricos. O objetivo do presente trabalho consistiu na avaliação ultrassonográfica do plexo braquial pela via axilar, bem como a identificação dos nervos em relação a artéria axilar. Foram utilizados 50 animais da espécie canina, sem distinção de raça, sexo e idade. Em todos os animais administrou-se propofol (3 mg/kg) através de um acesso venoso pré-instalado. Os animais foram mantidos sonolentos, porém facilmente despertáveis durante todo o procedimento. Após posicionamento do animal e iniciada a avaliação ultrassonográfica com a identificação das estruturas vasculares e nervosas, foi introduzida uma agulha eletricamente isolada guiada por estimulador de nervo periférico, obtendo-se, assim, resposta motora adequada para cada nervo visualizado por meio de uma corrente estimuladora de 0,5 mA. O exame teve como objetivo identificar a artéria axilar e os nervos radial, mediano e ulnar, e anotar suas posições. Para relacionar os nervos à artéria axilar, a região a ser estudada foi dividida em quatro setores. Em todos os pacientes estudados foram identificados os nervos: mediano localizado na região craniolateral (setor 4) em 8% dos pacientes e na região craniomedial (setor 1) em 92%; nervo radial na região craniomedial (setor 1) em 2% dos pacientes, caudomedial (setor 2) em 92% e caudolateral (setor 3) em 6%; nervo ulnar encontrado na região craniolateral (setor 4) em 2% dos animais e na região craniomedial (setor 1) em 98%. Diante dos resultados, conclui-se que a artéria axilar, na abordagem estudada, facilita a identificação e posicionamento dos nervos com o auxílio do estimulador de nervos periféricos e da ultrassonografia.

The use of ultrasonography in regional anesthesia has grown rapidly in recent years, due to the great progress in the resolution of ultrasound images, allowing the visualization not only of vessels, but of nerve roots and peripheral nerves. The objective of the present study consisted in the ultrasonography evaluation of the brachial plexus by the axillary way, as well as the identification of the nerves in relation to the axillary artery. Fifty animals of the canine species were used, without distinction of race, sex and age. Propofol (3 mg/kg) was given in all animals via preinstalled venous access. The animals were kept drowsy but easily aroused throughout the procedure. After the positioning of the animal and the ultrasound evaluation with the identification of the vascular and nervous structures, an electrically isolated needle guided by a peripheral nerve stimulator was introduced, thus obtaining adequate motor response for each nerve visualized through a stimulating current of 0.5 mA. The objective of the test was to identify the axillary artery and the radial, median and ulnar nerves, and note their positions. To relate the nerves to the axillary artery, the region to be studied was divided into four sectors. In all the patients studied, nerves were identified: median located in the craniolateral region (sector 4) in 8% of patients and in the craniomedial region (sector 1) in 92%; radial nerve in the craniomedial region (sector 1) in 2% of patients, caudomedial (sector 2) in 92% and caudolateral (sector 3) in 6%; ulnar nerve found in the craniolateral region (sector 4) in 2% of the animals and in the craniomedial region (sector 1) in 98%. In view of the results, it was concluded that the axillary artery, in the approach studied, facilitates the identification and positioning of the nerves with the aid of the peripheral nerve stimulator and the ultrasonography.

Aspectos histoquímicos e imunoistoquímicos nos neoplasmas do sistema nervoso periférico / Histochemical and immunohistochemical features of peripheral nerve neoplasms

Doze casos de tumores do sistema nervoso periférico, sete schwannomas e cinco neurofibromas foram diagnosticados entre 1964 e 2004, em caninos e bovinos. Histologicamente, as células predominantes nos schwannomas eram fusiformes organizavam-se em paliçada ou em feixes aleatórios. Nos neurofibromas as células neoplásicas eram fusiformes e se originavam da periferia dos nervos formando ninhos e feixes. O tecido conjuntivo era mais abundante nos neurofibromas e os colágenos dos tipos I e III eram os principais constituintes desses neoplasmas. Os neurofibromas foram caracterizados por uma concentração alta e difusa de mastócitos, provavelmente devido à origem das células neoplásicas do perineuro e epineuro. A coloração de AgNOR não se mostrou eficiente como indicador de prognóstico nos neoplasmas analisados. Imunoistoquímicamente houve forte marcação para vimentina (100 por cento) e S100 (100 por cento) em ambos os tipos de tumor. A maioria dos schwannomas (75 por cento) foi positiva para a proteína ácida fibrilar glial; os neurofibromas só apresentaram marcação nas células de Schwann dos fascículos nervosos(AU)

A retrospective study of peripheral nerve tumors was made from 1964 to 2004. The tumors summed up 12, being seven schwannomas and five neurofibromas. Schwannomas were composed of spindle-shaped cells either in a palisading pattern or random bundles loosely textured and neurofibromas by spindle cells. The connective tissue components were more prevalent in neurofibromas with a characteristic deployment of collagens type I and III. In AgNOR techniques, both benign and malignant schwannomas and neurofibromas did not show differences. Mast cells stained by toluidine blue were more prevalent in neurofibromas which are rich in reactive endoneurium. Schwannomas (100 percent) and neurofibromas (100 percent) were positive for vimentin and S100 protein, so they prove to be reliable for the diagnosis of peripheral nerve tumors. GFAP marked cells were found in three schwannomas and in Schwann cells within neurofibromas(AU)

Morphometric evaluation of nerve fibers after surgical repair by allograft and tubular prothesis of the ulnar nerve in dogs / Avaliação morfométrica de fibras nervosas do nervo ulnar após reparação cirúrgica com auto-enxerto e prótese tubular em cães

The purpose of this study was to evaluate, by morphometric analysis, the regenerated nerve fibers of dogs, after 26 weeks of observation, in gaps of the ulnar nerves substituted by allografts and tubular prosthesis of silicone. The ulnar nerves of four dogs were processed for electron microscopic evaluation. Six fields, with 1750 µm², for each dog and each procedure, were photographed at 1880x. A morphometric computer based analysis (Sigma Scan - Jandel Co., USA) resulted in the following numbers (average numbers in micrometers). 1. ulnar nerve with tubular prosthesis- a: myelinated fiber diameter-5.12 ± 1.67. b: myelinated axon diameter: 4.08 ± 1.52. c: myelin sheath thickness-0.52 ± 0.18. d: unmyelinated axon diameter: 0.98 ± 0.37. 2. ulnar nerve with allograft- a: myelinated fiber diameter: 6.04 ± 2.27. b: myelinated axon diameter: 4.59 ± 1.95. c: myelin sheath thickness: 0.72 ± 0.23. d: unmyelinated axon diameter: 0.96 ± 0.40. The morphometric analysis after 26 weeks of nerve repair didnt show a significant difference between the two surgical procedures.

O objetivo da investigação foi o de comparar os resultados observados por meio da avaliação morfométrica de fibras nervosas regeneradas, em cães, após 26 semanas da reparação cirúrgica de falhas do nervo ulnar, através de auto-enxertos e próteses tubulares de silicone. Para cada procedimento foram utilizados quatro animais. Dos nervos regenerados e dos enxertos foram retirados segmentos para avaliação em nível de microscopia eletrônica. De cada corte foram amostrados seis campos distintos com 1,750 µm² cada, que foram fotografados com aumentos de 1.880 vezes. Através de sistema computadorizado de morfometria (SigmaScan - Jandel Co., USA), obtiveram-se os seguintes parâmetros: diâmetros das fibras mielínicas; diâmetros dos axônios mielínicos; espessuras das bainhas de mielina e diâmetros dos axônios amielínicos. Os nervos regenerados no interior das próteses tubulares apresentaram diâmetros das fibras mielínicas com média de 5,12 ± 1,67 µm; média dos diâmetros dos axônios mielínicos de 4,08 ± 1,52 µm; média das espessuras das bainhas de mielina de 0,52 ± 0,18 µm; média dos diâmetros dos axônios amielínicos de 0,98 ± 0,37 µm. Os enxertos apresentaram os seguintes valores: média dos diâmetros das fibras mielínicas de 6,04 ± 2,27 µm; média dos diâmetros dos axônios mielínicos de 4,59 ± 1,95 µm; média das espessuras das bainhas de mielina de 0,72 ± 0,23 µm; média dos diâmetros dos a

Brachial plexus variations in its formation and main branches

PURPOSE: The brachial plexus has a complex anatomical structure since its origin in the neck throughout its course in the axillary region. It also has close relationship to important anatomic structures what makes it an easy target of a sort of variations and provides its clinical and surgical importance. The aims of the present study were to describe the brachial plexus anatomical variations in origin and respective branches, and to correlate these variations with sex, color of the subjects and side of the body. METHODS: Twenty-seven adult cadavers separated into sex and color had their brachial plexuses evaluated on the right and left sides. RESULTS: Our results are extensive and describe a large number of variations, including some that have not been reported in the literature. Our results showed that the phrenic nerve had a complete origin from the plexus in 20% of the cases. In this way, a lesion of the brachial plexus roots could result in diaphragm palsy. It is not usual that the long thoracic nerve pierces the scalenus medius muscle but it occurred in 63% of our cases. Another observation was that the posterior cord was formed by the posterior divisions of the superior and middle trunks in 9%. In these cases, the axillary and the radial nerves may not receive fibers from C7 and C8, as usually described. CONCLUSION: Finally, the plexuses studied did not show that sex, color or side of the body had much if any influence upon the presence of variations.

OBJETIVOS: O plexo braquial apresenta uma estrutura anatômica complexa, desde sua origem, no pescoço, até sua ramificação terminal, na região axilar. Ele também apresenta relações importantes com outras estruturas anatômicas locais, o que o torna vulnerável ao aparecimento de uma série de variações anatômicas, marcando sua importância clínica e cirúrgica. Os objetivos desse estudo foram de descrever as variações anatômicas do plexo braquial, desde sua origem até seus ramos terminais e correlacionar essas variações com o sexo e a cor dos indivíduos, bem como com o lado do corpo estudado. MÉTODOS: Vinte e sete cadáveres adultos, separados em sexo e cor, tiveram seus plexos braquiais avaliados à direita e à esquerda. RESULTADOS: Nossos resultados são extensos e descrevem um grande número de variações, incluindo algumas ainda não descritas na literatura. Nossos resultados mostram que o nervo frênico apresentou sua origem diretamente no plexo braquial em 20% dos casos. Assim, uma lesão das raízes do plexo braquial poderia resultar em uma inexplicada paralisia diafragmática. Não é esperado que o nervo torácico longo passe através do músculo escaleno médio entretanto, esse fato foi observado em 63% de nossos casos. Outra observaçõa foi a formação do fascículo posterior pelas divisões posteriores dos troncos superior e médio em 9% dos casos. Nesses casos, os nervos axilar e radial poderão não receber fibras de C7 e C8, como normalmente descrito na literatura. CONCLUSÃO: Os plexos braquiais estudados não mostraram que o sexo, a cor ou o lado do corpo influenciam de maneira importante na presença de variações anatômicas dessa estrutura.

Brachial plexus variations in its formation and main branches

PURPOSE: The brachial plexus has a complex anatomical structure since its origin in the neck throughout its course in the axillary region. It also has close relationship to important anatomic structures what makes it an easy target of a sort of variations and provides its clinical and surgical importance. The aims of the present study were to describe the brachial plexus anatomical variations in origin and respective branches, and to correlate these variations with sex, color of the subjects and side of the body. METHODS: Twenty-seven adult cadavers separated into sex and color had their brachial plexuses evaluated on the right and left sides. RESULTS: Our results are extensive and describe a large number of variations, including some that have not been reported in the literature. Our results showed that the phrenic nerve had a complete origin from the plexus in 20% of the cases. In this way, a lesion of the brachial plexus roots could result in diaphragm palsy. It is not usual that the long thoracic nerve pierces the scalenus medius muscle but it occurred in 63% of our cases. Another observation was that the posterior cord was formed by the posterior divisions of the superior and middle trunks in 9%. In these cases, the axillary and the radial nerves may not receive fibers from C7 and C8, as usually described. CONCLUSION: Finally, the plexuses studied did not show that sex, color or side of the body had much if any influence upon the presence of variations.

OBJETIVOS: O plexo braquial apresenta uma estrutura anatômica complexa, desde sua origem, no pescoço, até sua ramificação terminal, na região axilar. Ele também apresenta relações importantes com outras estruturas anatômicas locais, o que o torna vulnerável ao aparecimento de uma série de variações anatômicas, marcando sua importância clínica e cirúrgica. Os objetivos desse estudo foram de descrever as variações anatômicas do plexo braquial, desde sua origem até seus ramos terminais e correlacionar essas variações com o sexo e a cor dos indivíduos, bem como com o lado do corpo estudado. MÉTODOS: Vinte e sete cadáveres adultos, separados em sexo e cor, tiveram seus plexos braquiais avaliados à direita e à esquerda. RESULTADOS: Nossos resultados são extensos e descrevem um grande número de variações, incluindo algumas ainda não descritas na literatura. Nossos resultados mostram que o nervo frênico apresentou sua origem diretamente no plexo braquial em 20% dos casos. Assim, uma lesão das raízes do plexo braquial poderia resultar em uma inexplicada paralisia diafragmática. Não é esperado que o nervo torácico longo passe através do músculo escaleno médio entretanto, esse fato foi observado em 63% de nossos casos. Outra observaçõa foi a formação do fascículo posterior pelas divisões posteriores dos troncos superior e médio em 9% dos casos. Nesses casos, os nervos axilar e radial poderão não receber fibras de C7 e C8, como normalmente descrito na literatura. CONCLUSÃO: Os plexos braquiais estudados não mostraram que o sexo, a cor ou o lado do corpo influenciam de maneira importante na presença de variações anatômicas dessa estrutura.