Six asymmetric bilateral additional heads of biceps brachii muscle observed in a cadaver / Seis cabezas adicionales bilaterales asimétricas del músculo bíceps braquial observadas en un cadáver

SUMMARY: Anatomic variation of the biceps brachii muscle (BBM) is frequently observed; its pattern is diverse and clinically important. During the educational dissection of a 78-year-old Korean male cadaver, six additional asymmetrical heads of the biceps brachii muscle (BBM) were found on both sides. On the right side, two additional heads originated from the humerus; the musculocutaneous nerve passed between these heads and the short head of the BBM. Four additional heads were found on the left side, anterior to the BBM, one of which originated from the pectoralis major muscle. Posterior to the BBM, two heads of tendons originated from the coracobrachialis muscle and one head of the muscle belly originated from the humerus. The left musculocutaneous nerve pierced the coracobrachialis muscle and continued distally passing between the short head of the BBM and the additional heads located posterior to the BBM. It then gave off the variant musculocutaneous nerve to the median nerve. On both sides, the short and long heads of the BBM had normal origins, insertions, and courses. This novel variation has various clinical and embryological implications.

RESUMEN: Con frecuencia se observa una variación anatómica del músculo bíceps braquial (MBB); su patrón es diverso y clínicamente importante. Durante la disección de un cadáver masculino coreano de 78 años, se encontraron seis cabezas asimétricas adicionales del músculo bíceps braquial en ambos lados. En el lado derecho, dos cabezas adicionales se originaban en el húmero; el nervio musculocutáneo atravesaba entre estas cabezas y la cabeza corta del MBB. Se encontraron cuatro cabezas adicionales en el lado izquierdo, anterior al MBB, una de las cuales se originaba en el músculo pectoral mayor. Posterior al MBB, dos cabezas tendinosas se originaban en el músculo coracobraquial y una cabeza de vientre muscular se originaba en el húmero. El nervio musculocutáneo izquierdo perforaba el músculo coracobraquial y continuaba distalmente pasando entre la cabeza corta del MBB y las cabezas adicionales ubicadas por detrás del MBB. Luego emitía la variante el nervio musculocutáneo al nervio mediano. En ambos lados, las cabezas corta y larga del MBB tenían orígenes, inserciones y trayectos normales. Esta nueva variación tiene varias implicaciones clínicas y embriológicas.

Two cases of variations of musculocutaneous nerve communication with the median nerve / Dos casos de variaciones de la comunicación del nervio musculocutáneo con el nervio mediano

SUMMARY: To know the nerve variations of brachial plexus and its branches is very important in the management of upper limb nerve injuries. Variations of the brachial plexus are not uncommon, but types of variations are diverse. The unusual communication branches between the musculocutaneous nerve (MCN) and the median nerve (MN) in course were found during routine dissection on the two different left arms of formalin fixed male cadavers. Depending on the position related to the coracobrachial muscle (CBM), one MCN pierced the CBM, the other did not in the two cases. The branches of MCN emerged interior to the coracoid process to innervate the CBM. The present case reports of anatomical variations of nerves can help to manage nerve injuries and plan surgical approaches during surgical procedures.

RESUMEN: Conocer las variaciones nerviosas del plexo braquial y sus ramas es muy importante en el tratamiento de las lesiones nerviosas de los miembros superiores. Las variaciones del plexo braquial no son infrecuentes, sin embargo los tipos de variaciones son diversos. Los ramos inusuales de comunicación entre el nervio musculocutáneo (NMC) y el nervio mediano (NM) en curso fueron descubiertos durante la disección de rutina en dos miembros superiores izquierdos de dos cadáveres de sexo masculino fijados con formalina. Un NMC atravesó el MCB, otro no lo hizo en los dos casos. Los ramos de NMC emergieron a nivel del proceso coracoideo para inervar el MCB. Los presentes informes de casos de variaciones anatómicas de los nervios pueden ayudar a tratar las lesiones nerviosas y planificar los abordajes quirúrgicos durante los procedimientos quirúrgicos.

Classification of the musculocutaneous nerve fetuses / Clasificación del nervio musculocutáneo en fetos

SUMMARY: The musculocutaneous nerve is a terminating branch of lateral cord of the brachial plexus and is formed from spinal roots of C5, C6 and C7. The anatomical variations of the musculocutaneous nerve (MCN) are not common, literary reports have described the different course of the MCN in the arm, however very few fetal studies have been conducted on the variations of the MCN. Therefore, the aim of this study was to describe the course of the MCN in fetuses and document variations, if any. In this study, a sample size of twenty-five fetuses were bilaterally dissected (n=50) using a stereomicroscope. The anatomy of the MCN was described using a classification system generated based on the findings of this study. Ethical clearance was obtained from Biomedical Research Ethics Committte (BE385/17). Type I (normal anatomy) of the MCN was found in 42/50 (84 %) of specimens in this study. This study found a few variations, viz. 1/50 (2 %) case of Type II (absent), 1/50 (2 %) Type III (communication between the MCN and MN, from the MN to the MCN), 4/50 (8 %) cases of Type IV (communication from the MCN to the MN) and 2/50 (4 %) cases of Type V (communication from the MCN to the MN, where the MCN does not pierce the coracobrachialis muscle). Therefore, this study provides evidence of variations of the MCN in fetuses that may help surgeons in the interpretation of abnormal innervation patterns in the arm.

RESUMEN: El nervio musculocutáneo es un ram terminal del fascículo lateral del plexo braquial y está formado por las raíces espinales de C5, C6 y C7. Las variaciones anatómicas del nervio musculocutáneo (NMC) no son comunes, los informes literarios han descrito el curso diferente del NMC en el brazo, sin embargo, se han realizado muy pocos estudios fetales sobre las variaciones de este nervio. Por lo tanto, el objetivo del estudio fue describir el curso del NMC en fetos y documentar las variaciones. En este estudio, una muestra de veinticinco fetos fue disecada bilateralmente (n = 50) usando un estereomicroscopio. La anatomía del NMC se describió mediante un sistema de clasificación en base a los hallazgos. La aprobación ética se obtuvo del Comité de Ética en Investigación Biomédica (BE385 / 17). El tipo I (anatomía normal) del NMC se encontró en 42/50 (84 %) de las muestras. Se observaron algunas variaciones, por ejemplo: 1/50 (2 %) caso de Tipo II (ausente), 1/50 (2 %) de Tipo III (comunicación entre NMC y nervio mediano (NM), de NM a NMC), 4/50 (8 %) casos de Tipo IV (comunicación del NMC al NM) y 2/50 (4 %) casos de Tipo V (comunicación del NMC al NM, donde el NMC no perfora el músculo coracobraquial). Este estudio proporciona evidencia de variaciones del NMC en fetos que puede ayudar a los cirujanos a interpretar patrones de inervación anormales en el brazo.

Positional anomaly between the brachial plexus and the scalene muscles, concomitant with an anomalous path of the musculocutaneous nerve: case report and clinical implication / Anomalía posicional entre el plexo braquial y el músculo escaleno anterior, concomitante con un trayecto anómalo del nervio musculocutáneo: reporte de un caso e implicancia clínica

Anatomical variations of the scalene muscles are frequent, as are those of the brachial plexus and its terminal nerves. Nonetheless, these variations are reported separately in the literature. The aim of this work is to present a variation of scalene muscles, concomitant with an abnormal path of the musculocutaneous nerve. During a routine dissection of the cervical region, axilla and right anterior brachial region in an adult male cadaver, a supernumerary muscle fascicle was located in the anterior scalene muscle, altering the anatomical relations of C5 and C6 ventral branches of the brachial plexus. This variation was related to an anomalous path of the musculocutaneous nerve that did not cross the coracobrachialis muscle. It passed through the brachial canal along with the median nerve. It then sent off muscular branches to the anterior brachial region and likewise, communicating branches to the median nerve. The concomitant variations of the brachial plexus and scalene muscles they are not described frequently. Knowledge of these variations improves diagnosis, enhancing therapeutic and surgical approaches by reducing the possibility of iatrogenesis during cervical, axillary and brachial region interventions.

Las variaciones anatómicas de los músculos escalenos son frecuentes, así como también las del plexo braquial y sus nervios terminales. Sin embargo la literatura científica las presenta por separado. El propósito de este trabajo es presentar una variación de los músculos escalenos concomitante con un trayecto anómalo del nervio musculocutáneo. Disección de rutina de región cervical, axila y región braquial anterior derechas realizada en un cadáver adulto de sexo masculino. Se encontró un fascículo muscular supernumerario para el músculo escaleno anterior que alteraba las relaciones anatómicas de los ramos ventrales C5 y C6 del plexo braquial. Esta variación estaba acompañada por un trayecto anómalo del nervio musculocutáneo, el cual no atravesaba al músculo coracobraquial y transitaba por el conducto braquial acompañando al nervio mediano. Desde allí enviaba a la región braquial anterior ramos musculares y al nervio mediano ramos comunicantes. Las variaciones conjuntas del plexo braquial y los músculos escalenos no se presentan con frecuencia. Conocerlas enriquece la capacidad diagnóstica, terapéutica y quirúrgica. Reduciendo la posibilidad de iatrogenia al intervenir en las regiones cervical, axilar y braquial.

The third head of the biceps brachii muscle perforated by the musculocutaneous nerve / La tercera cabeza del músculo bíceps braquial perforada por el nervio musculocutáneo

During an educational dissection, the third head of the biceps brachii muscle was found on the left side in a 63-yearold female Korean cadaver. The short and long heads showed normal morphology, and their courses were as follows: The third head was originated from the middle level of the humerus under the short head and inserted in the conjoined tendon of the long and short heads of the biceps brachii muscle. The musculocutaneous nerve penetrated the third head of the biceps brachii muscle and became the lateral cutaneous nerve of the forearm. The authors describe this novel case and discuss the clinical implications of such a variation.

Durante una disección educativa, la tercera cabeza del músculo bíceps braquial se encontró en el lado izquierdo en un cadáver coreano de 63 años de edad. La cabeza corta y la cabeza larga mostraron una morfología normal, y se presentaron de la siguiente forma: La tercera cabeza se originó en el nivel medio del húmero, inferior a la cabeza corta, y se insertó en el tendón unido de las cabezas larga y corta del músculo bíceps braquial. El nervio musculocutáneo penetró en la tercera cabeza del músculo bíceps braquial para transformarse en el nervio cutáneo lateral del antebrazo. Los autores describen este nuevo caso y discuten las implicaciones clínicas de esta variación.

Anatomic variations in relation to the origin of the musculocutaneous nerve: absence and non-perforation of the coracobrachialis muscle: anatomical study and clinical significance / Variaciones anatómicas en relación al origen del nervio musculocutáneo: ausencia y no perforación del músculo coracobraquial: estudio anatómico y significado clínico

The most frequent anatomic variations of the musculocutaneous nerve could be divided in two main groups: communicating branches with the median nerve and variations in relation to the origin, which in turn can be subdivided into absence of the nerve and non-perforation of the coracobrachialis muscle. Unusual clinical symptoms and/or unusual physical examination in patients with motor disorders, could be explained by anatomic variations of the musculocutaneous nerve. A total of 106 arms were evaluated, corresponding to 53 fresh male cadavers who were undergoing necropsy. The presence or absence of the musculocutaneous nerve was evaluated and whether it pierced the coracobrachialis muscle or not. The lengths of the motor branches and the distances from its origins to the coracoid process were measured. In 10 cases (9.5 %) an unusual origin pattern was observed, of which six (5.7 %) correspond to non-perforation of the coracobrachialis muscle and four (3.8 %) correspond to absence of the nerve. The length of the branch for the brachialis muscle was 37.7±15.4 mm and for the short and long heads of the biceps 27.6±11.7 mm and 33.2±10.1 mm respectively. The study showed that our population has similar prevalence of absence of the musculocutaneous nerve and non-perforation of the coracobrachialis muscle compared to previous reports in different populations. Moreover, there was no statistical correlation between the sides and the evaluated variables.

Las variaciones anatómicas más frecuentes del nervio musculocutáneo se pueden dividir en dos grupos principales: Ramas comunicantes con el nervio mediano y variaciones en relación al origen, que a su vez se pueden subdividir en la ausencia del nervio y la no perforación del músculo coracobraquial. Los síntomas clínicos inusuales y / o el examen físico inusual en pacientes con trastornos motores podrían explicarse por variaciones anatómicas del nervio musculocutáneo. Se evaluaron un total de 106 brazos, que corresponden a 53 cadáveres de machos frescos sometidos a necropsia. Se evaluó la presencia o ausencia del nervio musculocutáneo y si atravesó o no el músculo coracobraquial. Se midieron las longitudes de las ramas motoras y las distancias desde sus orígenes hasta el proceso coracoides. En 10 casos (9,5 %) se observó un patrón de origen inusual, de los cuales seis (5,7 %) corresponden a la no perforación del músculo coracobraquial y cuatro (3,8 %) corresponden a la ausencia del nervio. La longitud de la rama para el músculo braquial fue de 37,7 ± 15,4 mm y para las cabezas cortas y largas del bíceps 27,6 ± 11,7 mm y 33,2 ± 10,1 mm, respectivamente. El estudio mostró que nuestra población tiene una prevalencia similar de ausencia del nervio musculocutáneo y la no perforación del músculo coracobraquial comparado con informes previos en diferentes poblaciones. Además, no hubo una correlación estadística entre los lados y las variables evaluadas.

Anatomy of osterior antebrachial cutaneous nerve related to the lateral epicondyle and interepicondylar line / Anatomía del nervio cutáneo posterior del antebrazo relacionado con el epicóndilo lateral y la línea interepicondilar

Posterior antebrachial cutaneous nerve (PACN) is a branch of radial nerve supplying the skin of posterior forearm. Data regarding its anatomy remain insufficient especially the origin and number of branches. We dissected 101 upper extremities from 32 male and 20 female cadavers to expose the PACN. In all specimens, the nerve emerged from the deep fascia at the hiatus proximal to the interepicondylar line (IEL) with mean distances of 7.24 and 7.44 cm in males and females, respectively. Percentage of this distance to the arm length was 23.2 % and 26.1 % in males and females, respectively. After penetrating the deep fascia, the PACN coursed in the subcutaneous layer and crossed the IEL anterior to the lateral epicondyle (LE) in all cases. The mean distances from the crossing point to the LE along the IEL were 1.52 cm in males and 1.34 cm in females. Regarding the branches of PACN, at least 50 % of the specimens had up to 3 or 4 branches originating either proximal or distal to the hiatus. In two arms, one of these branches passed posterior to the LE. Moreover, there were communicating branches between the PACN and the lateral antebrachial cutaneous nerve in 9 specimens. Gender and side differences were found in some measurement parameters. These data are crucial for avoiding the PACN injury during surgical procedures around the elbow.

El nervio cutáneo posterior del antebrazo (NCPA) es un ramo del nervio radial que inerva la piel del antebrazo. Los datos acerca de su anatomía siguen siendo insuficientes en especial en cuanto a su origen y el número de ramos. Disecamos 101 miembros superiores de cadáveres pertenecientes a 32 hombres y 20 mujeres para exponer el NCPA. En todas las muestras, el nervio surgió de la fascia profunda en el hiato proximal a la línea interepicondilar (LIE) con distancias medias de 7,24 y 7,44 cm en hombres y mujeres, respectivamente. El porcentaje de esta distancia a la longitud del brazo fue 23,2 % y 26,1 % en hombres y mujeres, respectivamente. Después de penetrar la fascia profunda, el NCPA continuaba en el tejido subcutáneo y cruzaba la LIE anterior al epicóndilo lateral (EL) en todos los casos. Las distancias medias desde el punto de cruce del EL a lo largo de la LIE fueron 1,52 cm en hombres y 1,34 cm en mujeres. Con respecto a las ramos del NCPA, al menos 50 % de las muestras tenían hasta 3 o 4 ramos, ya fuesen proximales o distales al hiato. En dos de los brazos, uno de estos ramos pasó posterior al EL. Por otra parte, en 9 de las muestras se observó comunicación entre los ramos del NCPA y el nervio cutáneo antebraquial lateral. No se encontraron diferencias secundarias o de sexo en algunos parámetros de medición. Estos datos son esenciales para evitar las lesiones durante los procedimientos quirúrgicos alrededor del codo que involucren el NCPA.

Rare anatomical variation of the musculocutaneous nerve - case report / Rara variação anatômica do nervo musculocutâneo - Relato de caso

The clinical and surgical importance of anatomical knowledge of the musculocutaneous nerve and its variations is due to the fact that one of the complications in many upper-limb surgical procedures involves injury to this nerve. During routine dissection of the right upper limb of a male cadaver, we observed an anatomical variation of this nerve. The musculocutaneous nerve originated in the lateral cord and continued laterally, passing under the coracobrachialis muscle and then continuing until its first branch to the biceps brachialis muscle. Just after this, it supplied another two branches, i.e. the lateral cutaneous nerve of the forearm and a branch to the brachialis muscle, and then it joined the median nerve. The median nerve followed the arm medially to the region of the cubital fossa and then gave rise to the anterior intermediate nerve of the forearm. The union between the musculocutaneous nerve and the median nerve occurred approximately at the midpoint of the arm and the median nerve. Given that either our example is not covered by the classifications found in the literature or that it fits into more than one variation proposed, without us finding something truly similar, we consider this variation to be rare.

A importância clínica e cirúrgica do conhecimento anatômico do nervo musculocutâneo e de suas variações deve-se ao fato de que uma das complicações em diversos procedimentos cirúrgicos do membro superior envolve sua lesão. Em uma dissecação de rotina do membro superior direito de um cadáver masculino observamos uma variação anatômica desse nervo. O nervo musculocutâneo originou-se no fascículo lateral, seguiu lateralmente, passou sob o músculo coracobraquial e seguiu até seu primeiro ramo para o músculo bíceps braquial. Logo após forneceu mais dois ramos, o nervo cutâneo lateral do antebraço e um ramo para o músculo braquial, e então uniu-se ao nervo mediano. O nervo mediano seguiu medialmente no braço até a região da fossa cubital e deu então origem ao nervo intermédio anterior do antebraço. A união do nervo musculocutâneo com o nervo mediano aconteceu aproximadamente no ponto médio do braço e do nervo mediano. Tendo em vista que as classificações encontradas na literatura ou não abrangem nosso exemplo ou o mesmo se adequa a mais do que uma variação proposta, sem que tenhamos encontrado alguma fielmente semelhante, consideramos essa variação como rara.

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.

Third head of biceps brachii muscle, associated with musculocutaneous and median nerve bilateral communication and with a communicating branch between median nerve roots / Tercera cabeza del músculo bíceps braquial asociada a la comunicación bilateral de los nervios musculocutáneo y mediano y a un ramo comunicante entre las raíces del nervio mediano

Both biceps brachii muscle anatomical variations and the presence of communicating branches between the musculocutaneous nerve and the median nerve are common, and have clinical significance due to their connections and vulnerability. A case found during a routine dissection of the upper limb of a male cadaver is described, in which unilateral presence of a third head of the biceps brachii muscle coexists associated to a bilateral communication of the musculocutaneous nerve with the median nerve, and a unilateral communicating branch between the roots of median nerve. The morphological features and the prevalence of the case are presented, besides the discussion of its clinical significance.

Tanto las variaciones anatómicas del músculo bíceps braquial como la presencia de ramos comunicantes entre los nervios musculocutáneo y mediano son frecuentes y tienen importancia clínica, debido a sus relaciones y vulnerabilidad. Se describe un caso encontrado durante una rutina de disección de los miembros superiores de un cadáver masculino, en el que coexiste la presencia unilateral de una tercera cabeza del músculo bíceps braquial asociada a una comunicación bilateral entre los nervios musculocutáneo y mediano junto a un ramo comunicante unilateral entre las raíces del nervio mediano. Se presentan sus características morfológicas, su prevalencia y se discute su importancia clínica.

Múltiples Variaciones Musculares y Neurovasculares en los Miembros Superiores: Presentación de Caso / Multiple Muscle and Neurovascular Variations in the Upper Limbs: Case Report

Se presenta un raro caso de múltiples variaciones en los miembros superiores de un espécimen cadavérico de 45 años de género masculino, del laboratorio de morfología de la Universidad Industrial de Santander (Bucaramanga-Colombia). Se observó variaciones musculares (presencia bilateral de cabezas adicionales del bíceps braquial y del musculo flexor largo del pulgar, agenesia del palmar largo derecho), nerviosas (anastomosis entre mediano y nervio musculocutáneo, y entre ulnar y mediano al nivel palmar superficial). Adicionalmente, presentó el origen de la arteria radial izquierda desde el segmento superior de la braquial. Estas diversas expresiones morfológicas determinan relevantes implicaciones clínicas y deben tenerse en cuenta en los diferentes abordajes quirúrgicos de los miembros superiores.

It is presented a rare case of multiple variations in the upper limbs of a 45 years old male cadaver specimen, ownership of the morphology laboratory of the Universidad Industrial de Santander (Bucaramanga, Colombia). Muscle variations were observed (presence of both additional heads of the biceps brachii and the flexor pollicis longus, agenesis of right palmaris longus), nervous variations (anastomosis between median and musculocutaneous nerve and between ulnar and median at superficial palmar level). Additionally it presented the radial artery origin from upper left segment of the brachial artery. These various morphological expressions determine relevant clinical implications and should be taken into account in the various surgical approaches to the upper limbs.

Comunicación masiva del ramo superficial del nervio radial con el nervio cutáneo antebraquial lateral, un análisis morfométrico: 1+1 < 2 / Massive communication between the superficial branch of radial nerve and the lateral cutaneous nerve of the forearm, a morphometric study: 1+1 < 2

La distribución de los ramos nerviosos sensitivos en el borde lateral y en el dorso de la mano han sido descritos con mayor exactitud en las últimas décadas, debido al avance de nuevas técnicas de diagnóstico, las cuales han permitido detectar que alrededor del 40 por ciento de la población examinada presenta algún grado de variación anatómica en el territorio de distribución de los nervios involucrados. Conocer el número de fibras que componen un ramo nervioso cutáneo de la región de la mano, ha adquirido mayor relevancia con el desarrollo de técnicas de microcirugía y de ultrasonografía, procedimientos que han demostrado la utilidad de este conocimiento en el diagnóstico y tratamiento de las lesiones nerviosas. Así, la arquitectura fascicular, el área adiposa y el área vascular de un ramo nervioso determinado constituyen datos que se ha demostrado se modifican con la edad y, en consecuencia, van condicionar la conducta terapéutica y el pronóstico de las lesiones nerviosas. En este caso presentamos una variación anatómica bilateral extremadamente rara, que involucra al ramo superficial del nervio radial y al nervio cutáneo lateral antebraquial; situación que aparece descrita en la literatura especializada sólo una vez y que modifica notablemente la inervación sensitiva del borde radial de la mano...

The distribution of sensory nerve branches in the lateral and the back of the hand have been described more accurately in recent decades due to advances in new diagnostic techniques, which have identified that about 40 percent of the population examined have some degree of anatomical variation in the distribution area of the sensitive nerves involved. The knowledge of the number of fibers forming a sensitive nerve of the hand has become more important with the development of microsurgical techniques and ultrasonography; procedures that have demonstrated the usefulness of this information in the diagnosis and treatment of nerve injuries. Thus, the fascicular architecture, adipose tissue area and the vascular area of a nerve branch, data that has been demonstrated that change with age, will determine the therapeutic and prognosis of nerve injuries. In this case we present an extremely rare and bilateral anatomical variation, involving the superficial branch of radial nerve and the lateral antebrachial cutaneous nerve, a situation that is described in the literature only once and which notably alter the sensory innervations of the radial edge of the hand...

Comunicación bilateral de los nervios músculocutáneo y mediano: aspectos morfológicos e importancia clínica / Bilateral communications of the musculocutaneous and median nerves, morphological aspects and clinical significance

Las comunicaciones entre los ramos terminales de plexo braquial son frecuentes y tienen importancia en la evaluación de traumatismos y procedimientos quirúrgicos de las regiones axilar y braquial. En este artículo presentamos un caso en el que durante la disección de rutina del miembro superior, se observó la presencia de comunicaciones bilaterales entre los nervios musculocutáneo y mediano. Los ramos comunicantes fueron descritos en su trayecto, relaciones y morfometría y se discutió acerca de la prevalencia e importancia clínica de estas comunicaciones.

Communication of the musculocutaneous and median nerves of the brachial plexus is common and is important in the evaluation of trauma and surgical procedures in axillary and brachial regions. This paper presents a case in which during a routine dissection of upper limb the presence of bilateral communication between musculocutaneous and medium nerves was observed. Trajectory of communicating branches was described, relation and morphometry was discussed with regard to prevalence and clinical significance of these communications.

Multiple variations of the branches of the brachial plexus with bilateral connections between ulnar and radial nerves / Múltiples variaciones de los ramos del plexo braquial con conexiones bilaterales entre los nervios ulnar y radial

During routine dissection of the upper limbs of a caucasian male cadaver, multiple variations of the branches of the brachial plexus were observed. On the left side, the musculocutaneous nerve was absent and the muscles of the anterior compartment of the arm were innervated by the median nerve. The median nerve was also formed from three roots viz; two from the lateral and one from the medial cord of the brachial plexus. On the right side, the musculocutaneous nerve contributed a long communicating branch to the median nerve in the distal half of the arm. There were also communicating branches between the ulnar and radial nerves in both limbs at the humeral level. The co-existence of these variations appears to be unique and has not been reported in the literature reviewed. The anatomic and clinical significance of these variations is discussed.

Fueron observadas durante una disección de rutina de los miembros superiores de un cadáver caucásico masculino, múltiples variaciones de los ramos del plexo braquial. En el lado izquierdo, el nervio musculocutáneo estaba ausente y los músculos del compartimento anterior del brazo estaban inervados por el nervio mediano. El nervio mediano se encontraba formado de tres raíces dos provenientes del fascículo lateral y uno del fascículo medial del plexo braquial. En el lado derecho, en la mitad distal del brazo, el nervio musculocutáneo generó un largo ramo comunicante con el nervio mediano. Además, en el brazo, en ambos miembros superiores existían ramos comunicantes entre los nervios ulnar y radial. La coexistencia de estas variaciones aparece ser única y no ha sido relatada en la literatura consultada. Son discutidas la significancia anatómica y clínica de estas variaciones.

Distribución de los nervios cutáneo dorsal medial y cutáneo dorsal intermedio en el hombre / Distribution of the medial dorsal cutaneous and intermediate dorsal cutaneous nerves in man

Gran parte de la inervación sensitiva del dorso del pie está dada por los ramos cutáneos del nervio fibular superficial, los nervios cutáneo dorsal medial (NCDM) y cutáneo dorsal intermedio (NCDI). El objetivo de esta investigación fue estudiar las divisiones de los NCDM y NCDI a nivel del tercio distal de la pierna y el dorso del pie, para contribuir con conocimientos específicos al abordaje quirúrgico de la región. Disecamos 19 piernas y pies en cadáveres de individuos adultos, masculinos, correspondientes al Departamento de Morfología de la Universidad de La Frontera de Temuco. Se dividió el dorso del pie, en tercios anterior, medio, posterior y luego, las divisiones observadas se padronizaron. La división de los NCDM y NCDI, en ramos medial y lateral, se observó en el tercio distal de la pierna, en un 47,4 por ciento y 52,6 por ciento respectivamente. La división del ramo medial de los NCDM y NCDI en ramos terminales, se observó en el tercio posterior del dorso del pie (42,2 por ciento) y en el tercio distal de la pierna (21,1 por ciento), respectivamente. La división del ramo lateral de los NCDM y NCDI en ramos terminales, se observó en el tercio posterior del dorso del pie (21,1 por ciento) y en el tercio anterior del dorso del pie (15,8 por ciento) respectivamente. La división de los ramos terminales del ramo medial de los NCDM y NCDI en nervios digitales dorsales, se observó en el tercio medio del dorso del pie en un 21,1 por ciento y 15,6 por ciento respectivamente. La división de los ramos terminales del ramo lateral de los NCDM y NCDI en nervios digitales dorsales, se observó en el tercio anterior del dorso del pie en un 15,8 por ciento, para ambos. Estos datos, pueden servir de referencia durante los procedimientos quirúrgicos realizados en la región, evitando lesiones iatrogénicas del área.

The sensory innervation of the dorsum of the foot is given by the cutaneous branches of the superficial fibular nerve, the medial dorsal cutaneous (MDCn) and intermediate dorsal cutaneous (IDCn) nerves. The aim of this research was to study the divisions of the MDCn and IDCn at the distal third of the leg and dorsum of the foot, to contribute expertise for the surgical approach in the región. Nineteen legs and feet of adult male cadavers, of the Department of Morphology, Universidad de La Frontera in Temuco, were dissected. We divided the dorsum of the foot in anterior, middle and posterior third, then the divisions were observed and patterned. The division of the MDCn and IDCn in medial and lateral branches was observed in the distal third of the leg, 47.4 percent and 52.6 percent respectively. The division of the medial branch of the MDCn and IDCn in terminal branches, was observed in the posterior third of the dorsum of the foot (42.2 percent) and in the distal third of the leg (21.1 percent), respectively. The division of the lateral branch of the MDCn and IDCn in terminal branches, was observed in the posterior third of the dorsum of the foot (21.1 percent) and in the anterior third of the dorsum of the foot (15.8 percent) respectively. The division of the terminal branches of the medial branch of the MDCn and IDCn in dorsal digital nerves was observed in the middle third of the dorsum of the foot at 21.1 percent and 15.6 percent respectively. The division of the terminal branches of the lateral branch of the MDCn and IDCn in dorsal digital nerves was observed in the anterior third of the dorsum of the foot at 15.8 percent for both. These data may serve as a reference during surgical procedures performed in the region, avoiding iatrogenic injuries of the area.

Estudo anatômico do trajeto do nervo musculocutâneo em relação ao processo coracoide / Anatomical study of the musculocutaneous nerve in relation to the coracoid process

OBJETIVO: Os autores realizaram o estudo anatômico do trajeto do nervo musculocutâneo pela dissecção de 20 ombros em 10 cadáveres adultos frescos. MÉTODO: Mediu-se a distância da borda inferior do processo coracoide, ao ponto de penetração do ramo mais proximal do nervo musculocutâneo no músculo coracobraquial, denominada base. Partindo da borda inferomedial do processo coracoide, foi medida uma segunda distância até o ponto em que o fascículo lateral do plexo braquial cruza o músculo subclávio, sendo identificada como altura. A terceira mensuração foi da área triangular formada pelas duas primeiras medidas, denominada área. RESULTADOS: Observou-se que a média da base foi de 3,42cm, com variações de 2,38 a 4,30cm. A medida da altura foi em média 2,75cm, variando entre 1,03 a 3,80cm, e a média da área foi de 4,92cm², variando entre 1,22 a 7,99cm². CONCLUSÃO: Estas medidas são de grande importância, devido ao risco de lesão do nervo musculocutâneo nas abordagens cirúrgicas do ombro.

OBJETIVE: The authors performed an anatomic study of the trajectory of the muscle cutaneous nerve, dissecting 20 shoulders in 10 fresh adult corpses. METHOD: The distance was measured from the inferior edge of the coracoid process to the point of penetration of the nearest branch of the cutaneous nerve muscle of the coracobrachialis muscle, called base. Starting at the inferior-medial edge of the coracoid process, a second measurement was made to the point at which the lateral fascicle of the brachial plexus crosses the subclavius muscle, denominated height. The third measurement was of the triangular area formed by the two first measurements, denominated area. RESULTS: The average base length was 3.42 cm, varying from 2.38 cm to 4.40 cm. The height measurement was 2.74 cm, on average, varying between 1.03 cm and 3.80 cm. And the average area was 4.92 cm², varying between 1.22 cm² and 7.99 cm². CONCLUSION: These measurements are very important due to the risk of injury in the cutaneous nerve muscle in surgeries performed on the shoulder.

Padrones de inervación y localización biométrica de los puntos motores del músculo bíceps braquial en el hombre / Innervation patterns and biometric localization of the motor points of the brachial biceps muscle in man

La inervación del músculo bíceps braquial se torna importante debido a su constitución y a la acción que ejerce a nivel del codo, sobretodo cuando existen lesiones en nervios espinales o médula espinal alta. Con el objetivo de conocer con detalles la disposición de sus nervios y localizar desde el punto de vista biométrico sus puntos motores, se estudiaron 46 miembros superiores de 23 cadáveres formolizados de individuos brasileños, adultos, en los cuales se consideró el número de ramos, longitud, nivel de origen y puntos de penetración en el vientre muscular respecto a una línea trazada entre los epicóndilos humerales (LBE). El nervio musculocutáneo envía un ramo para el músculo en estudio como un ramo común que luego se dividió para sus dos cabezas en 19 casos (41,3%); ramos independientes para cada cabeza se encontraron en las muestras restantes (58,7%). Con respecto al número de ramos, la cabeza larga recibió un ramo (R1) en 35 casos (76,1%), dos ramos (R1 y R2) en 9 casos (19,6%) y tres (R1,R2 y R3) en 2 casos (4,3%); para la cabeza corta se observó un ramo en 39 casos (84,7%), dos en 5 casos (10,9%) y tres en 2 casos (4,3%). Cada uno de los ramos dirigidos a las cabezas del músculo bíceps se dividió en ramos secundarios (RS). Para la cabeza corta, el ramo principal se dividió en 2 RS en 20 casos; en 3 RS en13 casos; en 4 RS en 4 casos, siendo directo sin dividirse en 2 casos. Para la cabeza larga el ramo principal se dividió en 2 RS en 16 casos; en 3 RS en 13; en 4 RS en 3; en 5 RS en un caso y en 6 RS en 1 caso y en una muestra, el ramo principal penetró en el vientre muscular sin dividirse. Los RS penetraron a niveles variables en el vientre muscular. Los resultados obtenidos pueden servir de referencia para procedimientos de punción en los puntos motores o en estudios electromiográficos.

The biceps brachii muscle innervation is important due to its constitution and its function in the elbow joint, mainly when there are in spinal nerves damages or high spinal cord. The purpose of this study was determine with details the nerves disposition of this muscle and locate its motor points. The upper limbs of 23 formolized cadavers of adult Brazilian individuals were studied, in whose it recorded the number of branches, length, origin levels and motor point localization. The localization were recorded using as reference point a line between the humerus epicondyles. The musculocutaneous nerve send a branch for a studied muscle as a common trunk that divides in two branches, each to a different head of the biceps in 19 cases (41.3%); independent branches for each head were observed in the other cases (58.7%). The long head received one branch in 35 cases (76.1%); two branches (B1, B2) in 9 cases (19.6%) and three branches (B1, B2, B3) in 2 cases (4.3%). Each branch divided in secondary branches (SB). In the short head the principal branch divided in two SB in 20 cases; in three SB in 13 cases; in fourth SB in 4 cases and not dividing in 2 cases. In the long head, the principal branch divided in two SB in 16 cases; in three SB in 13 cases; in fourth SB in 3 cases; in five SB in one case and in sixth SB in one case and not dividing in one case. The SB pierce in the muscular belly to different levels. These results can be to use as reference for the puncture procedures in the motor points or in electromyography studies.

Origen y trayecto anómalos del nervio musculocutáneo / Anomalus origin and traject of musculocutaneous nerve

El nervio musculocutáneo se origina del fascículo lateral en el plexo braquial y sus fibras emergen principalmente de las raíces nerviosas anteriores de C5 y C6. Durante la disección de rutina del plexo braquial en un cadáver formolizado, fue encontrada una variación del origen y trayecto de este nervio. El nervio musculocutáneo se originaba de la cara lateral del nervio mediano y después del origen, cruzaba anteriormente al músculo coracobraquial, sin perforarlo, de medial hacia lateral y de proximal hacia distal, para después ramificarse. Las variaciones anatómicas encontradas contribuyen para el estudio de la anatomía y sirven para el cirujano en intervenciones en la fosa axilar y en la parte anterior del brazo, previniendo, así, complicaciones operatorias.

The musculocutaneous is originated from the lateral fascicle in the brachial plexus and its fibers emerge mainly from the anterior nervous roots C5 and C6. During the routine dissection of the brachial plexus in a formolized corpse, its origin variation and passage was found. The nerve was originated on the lateral face of the median nerve and after its origin, crossed anteriorly to the coracobrachial muscle, without perforating it, from medial to lateral, proximal to distal, after to branch off. The anatomical variations found contribute to the anatomy study and they serve as alert for the surgeon in interventions in the axillary's cavity and in the previous store of the arm, preventing, thus, operational complications.

Absence of musculocutaneous nerve associated with a third head of biceps brachii muscle and entrapment of ulnar nerve

Variations in the formation of the brachial plexus and in the course of its branches are not as uncommon as was once thought. A description of the abnormalities and complexities of the anatomy of the upper arm is very important with regard to surgical approaches. This case study reports a combined absence of musculocutaneous nerve associated with a third head of biceps brachii muscle in the left upper arm of an adult male cadaver. Moreover, the left ulnar nerve is entrapped within the substance of the medial head of the triceps muscle. The clinical implications, as well as the possible clinical symptoms resulting from these anomalies are discussed

An anatomical study of the subcoracoid space

PURPOSE: To evaluate the amplitude of the subcoracoid space under maximum internal and external rotations of the humeral head and measure the distance between the apex of the coracoid process and the following anatomical structures: (a) point of entry of the musculocutaneous nerve and its branches into the coracobrachial muscles and into the short head of the biceps brachii muscle; (b) acromial artery; (c) lesser tubercle of the humerus. METHOD: Thirty shoulders of fresh cadavers, without any kind of shoulder pathology, (9 males and 6 females) were dissected, and the distances (in mm) were measured between the anatomical structures defined above and the apex of the coracoid process. RESULTS: The mean distance between the apex of the coracoid process and the musculocutaneous nerve was 49.2 mm (in all specimens a proximal branch of the nerve was identified 34.2 mm away from the apex of the coracoid process), which was not significantly different between the sexes or body sides; the mean distance between the apex of the coracoid process and the acromial artery was 12.4 mm, which was not significantly different between the sexes or body sides; the mean distance between the apex of the coracoid process and the lesser tubercle of the humerus, with the humeral head under internal rotation, was 10.6 mm in men and 8.6 mm in women, values that were significantly different between the sexes. DISCUSSION: In women, the smaller distance between the apex of the coracoid process and the lesser tubercle of the humerus in the arm internal rotation suggests a higher chance of impingement between those bone structures among the female sex.

OBJETIVO: Avaliar a amplitude do espaço subcoracóide em rotação máxima interna e externa da cabeça do úmero e medir a distância entre o ápice do processo coracóide e as seguintes estruturas anatômicas: (a) ponto de entrada do nervo musculocutâneo e suas ramificações nos músculos coracobraquiais e na cabeça curta do músculo bíceps do braço; (b) artéria acromial; (c) tubérculo menor do úmero. MÉTODO: Foram dissecados trinta ombros de cadáveres novos (nove do sexo masculino e seis do sexo feminino) sem nenhum tipo de patologia de ombro, tendo sido feita a medida (em mm) entre as estruturas anatômicas mencionadas acima e o ápice do processo coracóide. RESULTADOS: A distância média entre o ápice do processo coracóide e o nervo musculocutâneo foi 49,2 mm (em todas as amostras foi identificado um ramo proximal do nervo a 34,2 mm de distância do ápice do processo coracóide) sem significado estatístico em termos de sexo e lado do corpo; a distância média entre o ápice do processo coracóide e a artéria acromial foi 12,4 mm, sem significado estatístico em termos de sexo e lado do corpo; a distância média entre o ápice do processo coracóide e o tubérculo menor do úmero com a cabeça do úmero em rotação interna foi 10,6 mm nos homens e 8,6 mm nas mulheres, valores esses significativos em termos de sexo. DISCUSSÃO: Nas mulheres, a distância menor entre o ápice do processo coracóide e o tubérculo menor do úmero em rotação interna do braço sugere uma probabilidade maior de invasão entre aquelas estruturas ósseas no sexo feminino.