Brachial plexus variations in its formation and main branches

Abstract

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.<br>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...

Infraclavicular Topography of the Brachial Plexus Fascicles in Different Upper Limb Positions

“…Furthermore, the authors found that the musculocutaneous nerve did not pierce the coracobrachial nerve, different from the classical anatomical report of Moore et al (2013). Other studies also reported differences in topography and brachial plexus formation between gender, ethnicity, and body sites (Fazan et al, 2003). These variables could not be determined and discussed in the present study because only one formalinpreserved male cadaver was used.…”

A study of anatomical variations of median nerve in human cadavers

“…6 Badawoud (2003) in his study of 48 upper limbs, found median nerve to be formed by four roots in 1 (2.1%) and by three roots in 3 specimens (6.3%). 7 Fazan et al 2003 in their study of 54 upper extremities found median nerve to be formed by three roots in 28 (52%) limbs. 2 Gupta M et al (2005) reported a case of median nerve formation by union of two lateral and one medial root.…”

“…1 Descriptions of nerve variations are useful in clinical and surgical practice, as an anatomical variation can be the cause of a nerve palsy syndrome due to differing relations of a nerve with a related muscle. 2 Communication between nerves and unusual branching patterns of nerves are also extremely important with respect to compressive neuropathies of the upper extremity. These are significant sources of misdiagnosis.…”

Article de synthèse: considérations anatomiques pour l’échoguidage lors de l’anesthésie régionale du cou et des membres supérieurs

“…Formation of the posterior cord by divisions of the superior and middle trunks without contributory C [7][8] fibres to the axillary and radial nerves has a 9% incidence. 36 The posterior cord may be absent in 3.5%, and the median nerve roots may fail to join and travel separately anteromedial to the axillary and branchial arteries. Variation in the formation and branching of brachial plexus nerve fibres will directly impact on the clinical assessment of upper limb innervations, and aberrant or absent nerves will impact on their ability to be localized on ultrasound examination.…”

“…With pre-fixation, the phrenic nerve can have its complete origin from the brachial plexus occurring in up to 20% of cases. 36 An accessory phrenic nerve may arise from the nerve to the subclavius muscle and travel anterior to the subclavian vein rather than posterior to it. Such variation can have clinical consequences when inadvertent anesthesia of the phrenic nerve results in hemidiaphragmatic paresis and reduction in forced vital capacity.…”