The innervation of the biceps brachii and brachialis muscles in specimens with a high incidence of an accessory biceps head.

We describe the patterns of motor branches to the elbow flexors in 106 fresh-frozen cadaveric upper extremities from 53 donors of the Latin American mestizo race. We identified a 20% incidence of an accessory biceps head. The innervation patterns to this accessory head were specifically described and added to the Yang classification as Type IV for the biceps and Type III for the brachialis. The patterns arising from the musculocutaneous nerve to the biceps brachii were of Type I in 69%, Type II in 9%, Type III in 7% and Type IV in 11%, and to the brachialis of Type I in 77%, Type II in 11% and Type III in 9%. In 4%, the branches did not originate from the musculocutaneous nerve. We hypothesize that the branch to the accessory biceps head might be considered as a donor for nerve transfer in selected brachial plexus injuries.

Communication between the musculocutaneous and median nerves in the arm: an anatomical study and clinical implications.

OBJECTIVE: To determine the frequency and features of communication between the musculocutaneous nerve (MCN) and median nerve (MN) in a sample of the Colombian population, and assess its clinical implication. METHODS: The arms of 53 cadaver specimens that had been subjected to necropsy at the National Institute of Forensic Medicine, in Bucaramanga, Colombia, were studied. The structures of the anterior compartment of the arm were dissected and characterized regarding the presence of communication between the MCN and MN. RESULTS: A communicating branch was found in 21/106 upper limbs (19.8%), occurring bilaterally in 10 (47.6%) and unilaterally in 11 (52.4%), without significant difference regarding the side of occurrence (p = 0.30). In 17% of the cases, there was MCN-MN communication in which the communicating branch was seen leaving the MCN after piercing the coracobrachialis muscle (Type I). In 2.8%, the connection was from the MN to the MCN (Type II). The length of the communicating branch was 57.8 ± 33.4 mm. The distances from the proximal and distal points of this branch to the coracoid process were 138 ± 39.4 mm and 188 ± 48.3 mm, respectively. The communicating branch was located mostly in the middle third of the arm. CONCLUSIONS: The frequency of MCN-MN communication observed in the present study is in the middle of the range of what was reported in previous studies. MCN-MN connections need to be taken into account in diagnosing and managing peripheral nerve lesions of the upper limbs.

OBJETIVO: Determinar a frequência e características da comunicação entre os nervos músculo-cutâneo (MCN) e mediano (MN) em uma amostra da população colombiana, e avaliar sua implicação clínica. MÉTODOS: Os braços de 53 cadáveres foram avaliados em necropsia no National Institute of Forensic Medicine, em Bucaramanga, Colômbia. As estruturas do compartimento anterior do braço foram dissecadas e caracterizadas em relação à presença de comunicação entre MCN e MN. RESULTADOS: Um ramo comunicante foi encontrado em 21/106 membros superiores (19.8%), ocorrendo bilateralmente em 10 (47,6%) e unilateralmente em 11 (52,4%), sem diferença significativa em relação ao lado da ocorrência (p = 0,30). Em 17% dos casos, havia uma comunicação entre MCN-MN na qual o ramo comunicante era visto emergindo do MCN após perfurar o músculo córaco-braquial (Tipo I). Em 2,8% dos casos a conexão foi do MN para o MCN (Tipo II). O comprimento do ramo comunicante foi 57,8 ± 33,4 mm. As distâncias entre os pontos proximal e distal deste ramo e o processo coracóide foi 138 ± 39,4 mm e 188 ± 48,3 mm, respectivamente. O ramo comunicante se localizou principalmente no terço médio do braço. CONCLUSÃO: A frequência da comunicação entre MCN-MN observada no presente estudo está na média daquela relatada em outros trabalhos. As conexões MCN-MN devem ser levadas em consideração no diagnóstico e no manejo das lesões dos nervos periféricos dos membros superiores.

Comunicação entre os nervos musculocutâneo e mediano no braço: estudo anatômico e implicações clínicas / Communication between the musculocutaneous and median nerves in the arm: an anatomical study and clinical implications

Determinar a frequência e as características da comunicação entre os nervos mus culocutâneo {NMC} e mediano {NM} em uma amostra da população colombiana e avaliar sua implicação clínica. Métodos: Os braços de 53 cadáveres foram avaliados em necropsia no Instituto Nacional de Medicina Forense, em Bucaramanga, Colômbia. As estruturas do compartimento anterior do braço foram dissecadas e caracterizadas em relação à presença de comunicação entre NMC e NM. Resultados: Um ramo comunicante foi encontrado em 21/106 membros superiores {19,8%}, ocorreu bilateralmente em 10 {47,6%} e unilateralmente em 11 {52,4%}, sem diferença signifi cativa em relação ao lado da ocorrência {p = 0,30}. Em 17% dos casos, havia uma comunicação entre NMC-NM na qual o ramo comunicante emergia do NMC após perfurar o músculo coracobraquial {Tipo I}. Em 2,8% dos casos a conexão foi do NM para o NMC {Tipo II}. O comprimento do ramo comunicante foi 57,8 ±33,4 mm. As distâncias entre os pontos pro ximal e distal desse ramo e o processo coracoide foram de 138 ± 39,4 mm e 188 ± 48,3 mm, respectivamente. O ramo comunicante se localizou principalmente no terço médio do braço. Conclusão: A frequência da comunicação entre NMC-NM observada no presente estudo está na média daquela relatada em outros trabalhos. As conexões NMC-NM devem ser levadas em consideração no diagnóstico e no manejo das lesões dos nervos periféricos dos membros superiores.

To determine the frequency and features of communication between the musculocutaneousnerve (MCN) and median nerve (MN) in a sample of the Colombian population,and assess its clinical implication.Methods: The arms of 53 cadaver specimens that had been subjected to necropsy at theNational Institute of Forensic Medicine, in Bucaramanga, Colombia, were studied. The structuresof the anterior compartment of the arm were dissected and characterized regardingthe presence of communication between the MCN and MN.Results: A communicating branch was found in 21/106 upper limbs (19.8%), occurring bilaterallyin 10 (47.6%) and unilaterally in 11 (52.4%), without significant difference regardingthe side of occurrence (p = 0.30). In 17% of the cases, there was MCN-MN communicationin which the communicating branch was seen leaving the MCN after piercing thecoracobrachialis muscle (Type I). In 2.8%, the connection was from the MN to the MCN(Type II). The length of the communicating branch was 57.8 ± 33.4mm. The distances fromthe proximal and distal points of this branch to the coracoid process were 138 ± 39.4mm and188 ± 48.3mm, respectively. The communicating branch was located mostly in the middlethird of the arm.Conclusions: The frequency of MCN-MN communication observed in the present study isin the middle of the range of what was reported in previous studies. MCN-MN connectionsneed to be taken into account in diagnosing and managing peripheral nerve lesions of theupper limbs.