Correlation between Elbow Flexor Muscle Strength and Needle Electromyography Parameters after Musculocutaneous Nerve Injury / 法医学杂志

OBJECTIVES@#To explore the changes of elbow flexor muscle strength after musculocutaneous nerve injury and its correlation with needle electromyography (nEMG) parameters.@*METHODS@#Thirty cases of elbow flexor weakness caused by unilateral brachial plexus injury (involving musculocutaneous nerve) were collected. The elbow flexor muscle strength was evaluated by manual muscle test (MMT) based on Lovett Scale. All subjects were divided into Group A (grade 1 and grade 2, 16 cases) and Group B (grade 3 and grade 4, 14 cases) according to their elbow flexor muscle strength of injured side. The biceps brachii of the injured side and the healthy side were examined by nEMG. The latency and amplitude of the compound muscle action potential (CMAP) were recorded. The type of recruitment response, the mean number of turns and the mean amplitude of recruitment potential were recorded when the subjects performed maximal voluntary contraction. The quantitative elbow flexor muscle strength was measured by portable microFET 2 Manual Muscle Tester. The percentage of residual elbow flexor muscle strength (the ratio of quantitative muscle strength of the injured side to the healthy side) was calculated. The differences of nEMG parameters, quantitative muscle strength and residual elbow flexor muscle strength between the two groups and between the injured side and the healthy side were compared. The correlation between elbow flexor manual muscle strength classification, quantitative muscle strength and nEMG parameters was analyzed.@*RESULTS@#After musculocutaneous nerve injury, the percentage of residual elbow flexor muscle strength in Group B was 23.43% and that in Group A was 4.13%. Elbow flexor manual muscle strength classification was significantly correlated with the type of recruitment response, and the correlation coefficient was 0.886 (P<0.05). The quantitative elbow flexor muscle strength was correlated with the latency and amplitude of CMAP, the mean number of turns and the mean amplitude of recruitment potential, and the correlation coefficients were -0.528, 0.588, 0.465 and 0.426 (P<0.05), respectively.@*CONCLUSIONS@#The percentage of residual elbow flexor muscle strength can be used as the basis of muscle strength classification, and the comprehensive application of nEMG parameters can be used to infer quantitative elbow flexor muscle strength.

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.

Absence of Musculocutaneous Nerve: A Rare Anatomical Variation

Neural variation of the brachium constitutes a significant anatomical and clinical entity. The absence of Musculocutaneous Nerve is occasional in humans and accordingly there may be unforeseen clinical implication regarding the atypical innervations of musculature otherwise supplied by the Musculocutaneous Nerve. The present study is an absence of Musculocutaneous nerve observed during our routine educational dissection, where the lateral cord of brachial plexus took over the area of supply of Musculocutaneous Nerve by giving both the muscular and sensory branches. Knowledge of these variations is important in surgeries and during the administration of regional anaesthesia near shoulder joint and upper arm.

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.

Brachial Plexus: Variations in Infraclavicular Part and their Significance

Introduction: Brachial plexus extends from the neck to the axilla and gives motor and sensory nerves to the upper limb. Thebrachial plexus has two parts supraclavicular and infraclavicular parts.Material and Methods: The present study was carried out on 15 adult human cadavers (15 specimens of the right and leftside of the upper limb) in the Department of Anatomy, Government Medical College and Hospital, Chandigarh. All the cadaverswere male.Observations: Of 30 cases, one specimen (3.34%) had variation in the arrangement of all cords (lateral, medial, and posterior)respective to the 3rd part of axillary artery, i.e., all three t cords lie lateral to 3rd part of axillary artery. In one case (3.34%), it wasobserved that lateral cord gave separate branch to coracobrachialis muscle. Musculocutaneous nerve passes straight downwardplaced between biceps brachii and brachialis. Musculocutaneous nerve continues as lateral cutaneous nerve of forearm. Inanother two cases (6.66%), there is communication between musculocutaneous and median nerve. Five cases (16.66%) hadvariations in the formation of median nerve. Here, median nerve was formed from three roots of two roots were originating fromlateral cord and one root from medial cord. In three cases (10%), there is higher origin of median nerve by joining of its tworoots. In one case (3.34%), there are two upper subscapularis nerves from the posterior cord. Other branches of this cord arelower subscapular, nerve to latissimus dorsi, radial, and axillary nerve which is normal in their positions.Discussion: Development of brachial plexus starts at 34th–35th day of intrauterine life and definitive adult pattern is visible by46th–48th day of intrauterine life. The growing axons are regulated by chemoattractants and chemorepulsants in a site-specificfashion. Changes in the signaling pattern between mesenchymal cells and neuronal growth cones can lead to variations.Conclusion: These variations are important for surgeons, neurosurgeons, and plastic surgeons in their respective field inknowing area of loss, loss of muscle power as well as in designing various surgeries.

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.

Anatomical Variations In The Formation Of Median Nerve With Its Clinical Implication: A Cadaveric Study

Background: The brachial plexus is a major and complicated plexus that gives rise to a number of nerves to themuscles of the back and the upper limb .Median nerve (MN) is one of the terminal branches of the brachial plexus(BP). It is normally formed in the axilla by union of lateral and medial spinal roots, which arise from lateral andmedial cords of brachial plexus. The purpose of this study is to provide additional information about variationsin the formation of median nerve as its abnormal branching pattern constitutes a major importance in anatomical,clinical and surgical fields.Methods: Observational based descriptive study was made on sixteen cadavers comprising of 32 upper limbs,of which one specimen was female cadaver. The dissection was performed bilaterally on both upper limbs andthe axillary regions of the cadavers. Careful observation for the variation in the formation of median nerve hasbeen carried out. The finding was properly photographed for proper documentation.Results: It was observed that out of 32 upper limbs 5 (15.63%) showed anatomical variations in the formation ofmedian nerve, with its course, branching pattern and communication with musculocutaneous nerve. Among thevariations in 1(3.13%) median nerve was formed by the fusion of three roots, two from the lateral and one fromthe medial cord of the brachial plexus (BP). Further in 2(6.25%) medial root of medial cord receive additionalunusual small lateral root from lateral cord forms median nerve. In other 2(6.25%) median nerve also receivecommunication rami from musculocutaneous nerve at the lower third of the arm just below coracobrachialismuscle.Conclusion: The anatomical variations were not bilateral in any cadaver, hence 4 (12.50%) of the variationsoccurred more often on the left side, and 1(3.13%) occurred in right side. Therefore knowledge of such variationsis important for anatomists, radiologists, neurologists, anesthesiologists, and surgeons for proper clinicaldiagnosis. So, these variations should be well kept in mind.

Communication Between Musculocutaneous And Median Nerves: A Cadaveric Study

Introduction: The communication between musculocutaneous nerve and median nerve is an important anatomicalvariation to occur having serious implications during surgical procedures on arm if unnoticed and without priorknowledge.Materials and Methods: The present study was conducted in 80 upper limbs of 40 adult human cadavers (Female:10 and Male: 30) in the Department of Anatomy, Siddhartha Medical College (Government), Vijayawada and theDepartment of Anatomy, N.R.I. Medical College, Guntur over a period of 4 years (2014 to 2018) during educationaldissections.Results: The communication between musculocutaneous nerve and median nerve was observed in present study,which is classified in accordance with previous classifications described in the literature. In present study theincidence of communication between musculocutaneous nerve and median nerve is 25%.Conclusion: Prior knowledge of this communication between musculocutaneous and median nerves in the arm isimportant to avoid the surgical damage to the nerves and also explain unusual clinical presentation in shoulderinjuries

Bilateral Variations In The Branching Pattern Of The Lateral Cord Of Brachial Plexus: A Case Report

Variations in the branches of the brachial plexus are not uncommon. In the present report, variation in thebranching pattern of the lateral cord is described along with the absence of the musculocutaneous nerve. Thelateral cutaneous nerve of the forearm was a direct continuation of the lateral cord. These kinds of variations ofnerve branches are more prone to injuries during upper arm and axillary surgeries. Knowledge regardingvariations in the brachial plexus is utmost important for surgeons, anesthesiologist, clinicians and anatomists.

Brachial Plexus Injuries with Ulnar Musculocutaneous Transfer: 78 Cases Study Focused on Possible Postoperative Complications

Objective To analyze 78 cases of brachial plexus injury submitted to the Oberlin technique between 2003 and 2012. The potential complications of this technique were analyzed, especially motor damage or hypoesthesia of the hand. Method Medical records from patients with brachial plexus injuries at the levels of the C5-C6 and C5-C6-C7 vertebrae were retrospectively analyzed. Cases submitted to the Oberlin procedure with or without concomitant brachial plexus procedures between 2003 and 2012 were evaluated. The minimum follow-up period was of 1 year. In addition to the clinical examination, electromyography and magnetic resonance imaging (MRI) of the brachial plexus were used to diagnose and locate the nerve damage. Results A total of 78 surgical patients met the inclusion criteria. Postoperative neurological changes, mostly transient, were observed in 18 patients. Hypoesthesia in the ulnar side of the handwas observed in seven cases; neuropathic pain in five cases; allodynia in four cases, and hand motor loss in two cases. Conclusion Based on the results of the present case series, we conclude that there are few sequelae in the donor nerve territory compared with the benefit of the Oberlin technique on the recovery of elbow flexion after brachial plexus injuries.

Isolated musculocutaneous nerve injury following a pedestrian-automobile collision: A case report

@#Isolated musculocutaneous nerve (MCN) lesion is rare and usually associated with direct trauma. Along with the rarity of this condition, other muscles involved in elbow flexion, such as brachioradialis and pronator teres, can mask the weakness induced by the MCN injury and make it difficult to identify it. Here, we report a 17-year-old patient with isolated MCN palsy following a single episode of anterior shoulder contusion. A lack of suspicion for this rare condition delayed diagnosis until 7 months post injury, when atrophy of muscles in the left upper arm became prominent and weakness of the elbow flexors persisted. After 6 months of rehabilitation therapy rather than undergoing surgical exploration, elbow flexor strength was nearly fully recovered but sensory symptoms remained. The mechanism of injury is speculated to be a sudden overloading of the anterior shoulder with extension and external rotation, which overstretched and compressed the MCN within the coracobrachialis muscle where the nerve is relatively fixed. Although isolated peripheral nerve injury is rare, it can be caused by a single episode of vigorous impact. Therefore, even in patients without any external wounds, careful physical examination with suspicion of peripheral nerve injury as one of the differential diagnoses is needed.

Does cognitive capacity interfere with the outcome of oberlin transfer? / A capacidade cognitiva interfere no resultado da cirurgia de oberlin?

ABSTRACT Objective: To determine the relationship between the functional outcome achieved following Oberlin transfer, the cognitive level of the patient, and the time elapsed between the trauma event and surgery. Methods: Eighteen patients with a traumatic injury to the brachial plexus (C5-C6 and C5-C7) were evaluated. Seventeen (94.4%) patients were males and one (5.6%) was female, with a mean age of 29.5 years (range 17-46 years). We evaluated the active range of motion, elbow flexion strength, and Disabilities of the Arm, Shoulder and Hand (DASH) and determined the correlation between the procedural outcome and the patient's cognitive level, as assessed by the Mini-Mental State Exam (MMSE). Results: We found statistically significant correlations between the MMSE scale and strength recovery (84.4%, p<0.001), which was classified as excellent, and between the MMSE and British Medical Research Council (BMRC) scales (78.4%, p>0.001), which classified cognitive level as good. Conclusions: We found a positive correlation between cognitive capacity and functional outcome of patients submitted to Oberlin surgery. The time elapsed between trauma and the surgical procedure showed an inversely proportional correlation with the strength of recovery. Level of Evidence II, Retrospective Study.

RESUMO Objetivo: Determinar a relação entre o resultado funcional obtido com a cirurgia de Oberlin, o nível cognitivo do paciente e com o tempo decorrido entre o trauma e a cirurgia. Métodos: Foram analisados dezoito pacientes, sendo 17 homens (94,4%) e uma mulher (5,6%), com idade média de 29,5 anos (17 a 46 anos), com lesão traumática alta do plexo braquial (C5-C6 e C5-C7). Avaliamos a amplitude de movimento ativa, a força muscular de flexão do cotovelo e o questionário DASH (Disabilities of the Arm, Shoulder and Hand) e determinamos a correlação entre o resultado obtido e o nível cognitivo do paciente, avaliado pelo Mini Exame do Estado Mental (MEEM). Resultados: Observamos correlações de significância estatística entre MEEM e recuperação de força (84,4%, p<0,001), classificada como ótima; MEEM e BMRC - British Medical Research Council (78,4%, p> 0,001), classificada como boa. Conclusões: Verificamos correlação positiva entre a capacidade cognitiva e os resultados funcionais dos pacientes submetidos à cirurgia de Oberlin. O tempo decorrido entre o trauma e o procedimento cirúrgico apresenta uma relação inversamente proporcional com a recuperação da força. Nível de Evidencia II, Estudo retrospectivo.

Variation Of Roots In The Formation Of Median Nerve

Background: Median nerve formation exhibits several variations in the form of additional roots and /orcommunications which are relevant to the surgical explorations of shoulder, axilla and arm.Aim: To study the variations in the formation of median nerve and its communications with musculocutaneousnerve in cadaveric upper limbs.Materials and Methods: The study was done in 34 formalin fixed cadavers (68 upper limbs) and 10 isolatedlimbs. All cadavers were conventionally dissected and observed for median nerve formation and dissected up tocubital fossa for presence of any communications.Observations: Out of the 78 upper limbs dissected, 12 limbs (15.38%) showed two lateral roots and one medialroot contributing to the formation of median nerve. One case of bilateral presence of extra lateral root wasfound. The extra lateral root or communication from the musculocutaneous nerve was arising distal tocoracobrachialis in 2 cases and proximal to the muscle in 10 cases. In three cases, absence of musculocutaneousnerve was observed and median nerve was supplying either all or some muscles of the flexor compartment. Oneof the cases of absent musculocutaneous nerve had two medial roots and one lateral root that is a very rarecombination of variation not reported in the literature. In all cases of two lateral roots, the median nerve wasformed medial or anterior to axillary artery. So we observed median nerve variation in 16 upper limbs [20.51%]Conclusion: Thorough understanding of variations in the formation and communications of median nerve and itsvascular relations is important for successful surgical outcome and clinical interpretation of lesions of thenerve.

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.

Bilateral Absence Of Musculocutaneous Nerve: Report Of Two Cases

Anatomical variations involving the brachial plexus are not uncommon. Abnormal communications among thebranches of musculocutaneous nerve especially those involving the posterior division are widely reported dueto their significance in various surgical procedures performed in this region. During the routine gross anatomicaldissection, we observed the bilateral absence of musculocutaneous nerve in two male cadavers aged 60 and 65years and the muscles of anterior compartment of arm were innervated by the braches from the Median nerve. Incase 1, it was observed that in the right and left arm, branches from the median nerve supplied the muscles of theanterior compartment namely the coracobrachialis, biceps brachii and brachialis. The branch which innervatedthe brachialis muscle later continued as lateral cutaneous nerve of forearm. In case 2, Absence of MCN observedbilaterally wherein right arm, wherein, a single branch from median nerve supplied the coracobrachialis muscle.Another branch from the median nerve, after passing through the lower end of coracobrachialis, divided into anoblique and a vertical branch which supplied the biceps brachii and brachialis respectively. These anatomicalvariations in the course of musculocutaneous and median nerve should be considered during surgical proceduresand while performing nerve conduction studies.

A Study On Anatomical Variations In The Formation Of Brachial Plexus And Its Branches

Background: The variable course of the nerves may be the cause of many neuralgic pains of the superior extremity.The knowledge of percentage of variations may help the surgeons in treating the cases of trauma & entrapmentneuropathies.Materials and Methods: The present study in 70 upper limbs of 35 human cadavers over a period 1year at thedepartment of Anatomy at Siddhartha medical college and surrounding medical colleges around Vijayawada.The detailed examination of the following nerves that is musculocutaneous, median, ulnar, radial and axillarynerves was done in the arm and following variations were observed.Results: Communication between musculocutaneous and median nerves in eleven limbs. Musculocutaneousnerve was absent in our limbs. Median nerve supplied muscles of front of arm where musculocutaneous nervewas absent in one limb. Musculocutaneous nerve did not pierce coracobrachialis muscle in seven limbs. TheCommunication between radial and ulnar nerve in one limb.Conclusion: Lesions of communicating nerve may give rise to pattern of weakness that may impose difficulty indiagnosis. So it is important to be aware of the variations that are observed and discussed in our study. Knowledgeof these variations is important for neurologists, orthopaedicians and traumatologists as these may give rise tovariable clinical picture depending upon the variations present.

The Adherence of Musculocutaneous Nerve to Median Nerve Without Piercing Coracobrachialis Muscle – A Case Report

The brachial plexus has been reported to show different variations with its formation, course, branches and distribution patterns. During routine dissection in the department of Anatomy, College of Medicine and Health Sciences, Bahir Dar University. One such variation was observed, musculocutaneous nerve arises as usual from the lateral cord but unusually, it does not pierce the coracobrachialis muscle rather, the nerve unites with median nerve and forms common trunk and gives branches to the anterior compartment of the arm in the middle of the arm. Considering clinical importance, recognition and knowledge of such possible anatomical variation will be helpful in the field of neurology, anesthesia and surgery.

ANATOMIC STUDY OF THE NERVOUS COMMUNICATION BETWEEN THE MEDIAN AND MUSCULOUCUTANEOUS NERVE

ABSTRACT Objective: The aim of this study was to analyze the incidence of nerve communication between the musculocutaneous and median nerve . Methods: Anatomical dissection of 40 limbs from 20 fetal cadavers was performed at the Laboratory of Anatomy, Faculdade de Ciências Médicas e da Saúde da Pontifícia Universidade Católica de São Paulo . Results: A communicating branch was found in 10 upper limbs. In nine limbs there was a musculocutaneous-median anastomosis (type I); and in one limb there was a median-musculocutaneous anastomosis (type II) . Conclusion: It is very important to know these anatomical variations, especially when considering clinical examination, diagnostic, prognostic and surgical treatment. Level of Evidence IV, Case Series.