Bifurcated distal biceps brachii tendon coexisting with separated bicipital aponeurosis: a complex variational case report.

Variations appearing in biceps brachii muscle are common with accessory head, different origins, variant insertion, and different pattern of nerve innervation. However, variations appearing in both origin and insertion, and with other anomalous morphology at the same time are seldom. Here we report a complex variational case on the right arm of a 91-year-old Japanese female cadaver. The complex variations included (1) the biceps brachii muscle bifurcated at its distal ending; (2) the long head had its own tendon, which divided into two parts, i.e., a lateral part fused into the fascia between the brachioradialis and extensor carpi brevis, and a medial part attached to the radius about one centimeter ahead of the radial tuberosity; (3) the short head had an accessory origin from the shoulder capsule; (4) the bicipital aponeurosis was of two parts with an anterior superior layer formed by the long head and a posterior deep one formed by the short head; (5) the musculocutaneous nerve was especially underdeveloped that only innervated the coracobrachialis; (6) the existence of communicating branch between the musculocutaneous and median nerves, and the median nerve issued muscular branches to the biceps brachii and brachialis muscles, and (7) the brachioradial muscle had two accessory muscular bundles that originated from the fascia of the brachial muscle (proximal one) and from the bicipital aponeurosis (distal one).

Atypical branching of the musculocutaneous and median nerves with associated unusual innervation of muscles in the anterior compartment of the arm: case report and plea for extension of the current classification system.

PURPOSE: Variations of the peripheral nervous system in the upper limb, especially of the musculocutaneous and median nerves, are common, but closer attention to the knowledge of the variant anatomy should be paid to avoid iatrogenic injury or to understand the unusual clinical signs. METHODS: During a routine dissection course, bilateral variations were observed in a Central European male cadaver. RESULTS: Variable branching of the musculocutaneous and median nerves associated with atypical innervation of the muscles in the anterior compartment of the arm and other concomitant variations were found bilaterally. In both cases, the musculocutaneous nerve innervated only the coracobrachialis muscle and terminated inside the muscle belly. Branches to the biceps brachii and brachialis muscles arose either directly from the median nerve or its branches. On the right side, two communicating branches between the roots of the median nerve were noted, and a common medial cutaneous trunk originated from the lateral cord. On the left side, a communicating branch extended from the lateral cord to the medial root of the median nerve and a tributary to the axillary vein passed through a window formed by the roots of the median nerve and the communicating branch. CONCLUSION: There exist only few cases in the literature describing similar variations, but the present arrangement has not yet been reported to the best of our knowledge. With the proposed extension to the existing classification system, we aim to provide clearer orientation in the variability of the musculocutaneous and median nerves.

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.

Hypoplastic superficial brachioradial artery coexisting with atypical formation of the median and musculocutaneous nerves: a rare combination of unusual topographical relationships.

The use of the term "brachioradial artery" was introduced for the high origin of the radial artery. Although the prevalence of the brachioradial artery reported by different authors varies from 4.67 to 15.6%, the presence of the hypoplastic brachial segment of the brachioradial artery is rare with an occurrence rate of 0.83%. Moreover, in just 0.6% of cases the loop of the median nerve may be placed near half of the length of the brachial artery, as in the case described in our report. A comprehensive understanding of anatomical variations of neurovascular structures in the upper limb is of great clinical significance. The presented case report illustrates a rare manifestation of persistent primitive developmental relationships in the arterial pattern of the upper limb (persistent, hypoplastic brachial segment of the superficial brachioradial artery), coexisting with atypical formation of the median and musculocutaneous nerves. Anatomical variations of vessels and nerves may coexist which should be taken into account when performing vascular, reconstructive or orthopedic surgery.

Comentario al artículo 'Nuestra técnica de colgajo miocutáneo de pectoral mayor para reconstrucción de defectos cervicales' / No disponible

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Anomalous Innervation of the Median Nerve in the Arm in the Absence of the Musculocutaneous Nerve.

The brachial plexus innervates the upper extremities. While variations in the formation of the brachial plexus and its terminal branches are quite common, it is uncommon for the median nerve to innervate the muscles of the arm. During the dissection of an elderly male cadaver at the Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India, in 2016, the coracobrachialis muscle was found to be supplied by a direct branch from the lateral root of the median nerve and the musculocutaneous nerve was absent. The branches of the median nerve supplied the biceps brachii and brachialis muscles and the last branch continued as the lateral cutaneous nerve of the forearm. These variations may present atypically in cases of arm flexor paralysis or sensory loss on the lateral forearm. Knowledge of these variations is important in surgeries and during the administration of regional anaesthesia near the shoulder joint and upper arm.

A novel classification of musculocutaneous nerve variations: The relationship between the communicating branch and transposed innervation of the brachial flexors to the median nerve.

The musculocutaneous nerve innervates the brachial flexors; i.e., the coracobrachialis, biceps brachii, and brachialis. The musculocutaneous and median nerve sometimes share a communicating branch and also muscular branches to brachial flexors are sometimes transposed to median nerve. Because these variations constitute a potentially important clinical and surgical issue, we evaluated 130 upper limbs of 65 cadavers and 184 cases of musculocutaneous and median nerve variations in the literature and devised a novel system of classification that covers each pattern of variation. Our proposed classification was applicable in all of our cases and those previously reported. In addition, transposed innervation of the brachial flexors from the musculocutaneous nerve to the communicating branches was observed in one limb in our case series. In this case and all previously reported cases of transposed innervation of the brachial flexors, communicating branches between the musculocutaneous and median nerve were found and no brachial flexor branch arose from the musculocutaneous nerve distal to the communicating branches. Consequently, we established that, as per our novel classification, all patterns of communicating branches could be classified into five types and the patterns of transposed innervation of the brachial flexors into three types.

Bilateral communications between the median and musculocutanous nerves after piercing the last one the coracobrachialis muscle

In the dissection of a 79-year-old Chinese male cadaver, communications were established on both sides between the median and musculocutanous nerves. The musculocutaneous nerve (mcn) was the continuation of the lateral cord. After piercing the coracobrachialis muscle, the mcn gave rise to a communicating branch which directed downwards medially and ended in the median nerve (mn) at the level of upper arm. In the left arm, the mn was formed by three roots: one medial root from the medial cord and two lateral roots from the lateral cord

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Anatomical study of the musculocutaneous nerve branching pattern: application for selective neurectomy in the treatment of elbow flexors spasticity.

PURPOSE: Spastic flexion deformity of the elbow is mainly mediated by the biceps brachii and the brachialis muscles, innervated by the musculocutaneous nerve. Selective neurectomy of the musculocutaneous nerve showed promising results to relieve excessive spasticity in the long term but lacks of a consensual surgical strategy. The aim of the study was to describe the distal branching pattern of the motor branches of the musculocutaneous nerve in an attempt to develop guidelines for surgery. METHODS: Sixteen arms of fresh cadaver specimen were dissected. We recorded the site of each primary and terminal motor branch as a percentage of the distance from the coracoid process to the lateral epicondyle. RESULTS: The biceps muscle was innervated by one to five primary motor branches. The first branch emerged from the nerve at an average of 37.1% of the arm length, and the most distal terminal branch at 55.7%. The brachialis muscle received one to three primary branches. The first branch exited the nerve at an average of 51.7% of the arm length and the last terminal branch at 69.3%. The average number of terminal branches dedicated to the biceps and the brachialis muscles were, respectively, 7.9 and 6.5. CONCLUSIONS: According to our findings, we recommend to dissect the musculocutaneous nerve between 18 and 75% of the distance between the coracoid process and the lateral epicondyle to identify the motor terminal branches to the biceps brachii and the brachialis muscle, sparing sensory branches.

Rare communication between the musculocutaneous and median nerves in the forearm: its clinical significance.

Morphologic classifications of communication between musculocutaneous and median nerves are not based on the distribution and the function of the communicating branch. The authors report a rare case of such a communication with passage of the median nerve through the pronator teres muscle and discuss its clinical significance. The musculocutaneous nerve was divided into a lateral branch that continued to the lateral antebrachial cutaneous nerve and a medial branch that joined the median nerve in the forearm. The authors separated the nerve bundles and noted that the communicating branch derived from the sixth to seventh cervical nerves and supplied nerve fibers to the pronator teres muscle and the proper palmar digital nerve of the thumb. In addition, the median nerve penetrated the humeral head of the pronator teres muscle. Isolated musculocutaneous neuropathy with such a communication may cause unexpected symptoms such as sensory deficit in the palm and muscular weakness of the forearm and the thumb.

Absence of musculocutaneous nerve associated with variations of distribution patterns of the median nerve / Ausencia del nervio musculocutáneo asociada con variaciones de los patrones de distribución del nervio mediano

Variations in the brachial plexus and the distribution patterns of its branches are not uncommon. A communicating branch, which is the most frequent variation, often arises from musculocutaneous nerve to median nerve. However, the branches arising from lateral cord of the brachial plexus and median nerve instead of musculocutaneous nerve are very rare. Detailed description of the abnormalities is important for surgical procedures. Our case study reports the musculocutaneous nerve was absent, a branch from the medial cord innervated the coracobrachialis muscle and two branches from the median nerve innervated the biceps and brachialis muscles, respectively. Moreover, the median nerve gave off the lateral antebrachial cutaneous nerve. This report provides evidence of such possible anatomical variations to surgeons, anesthetists and neurologists during clinical practice.

Las variaciones en el plexo braquial y los patrones de distribución de sus ramos no son infrecuentes. Un ramo comunicante, que es la variante más frecuente, a menudo surge desde el nervio musculocutáneo al nervio mediano. Sin embargo, los ramos que surgen del fascículo lateral del plexo braquial y nervio mediano en vez de nervio musculocutáneo son muy raros. La descripción detallada de las anomalías es importante para procedimientos quirúrgicos. En nuestro caso el nervio musculocutáneo estaba ausente, un ramo del fascículo medial inervó el músculo coracobraquial y dos ramos del nervio mediano inervaron los músculos bíceps y braquial, respectivamente. Por otra parte, el nervio mediano originó al nervio cutáneo antebraquial lateral. Este informe proporciona evidencia de algunas variaciones anatómicas útiles para cirujanos, anestesistas y neurólogos durante la práctica clínica.

Incidences and clinical implications of communications between musculocutaneous nerve and median nerve in the arm: a cadaveric study / Incidencias e implicaciones clínicas de las comunicaciones entre el nervio musculocutáneo y nervio mediano en el brazo: un estudio cadavérico

OBJECTIVES: Variations such as communications between the median nerve and musculocutaneous nerve or in their abnormal branching pattern constitute a major concern in clinical and surgical field. Knowledge of these variations not only provides the clinician with a proper interpretation of the case, but also minimizes the complication in surgical approaches in this region. METHOD: We examined 50 isolated upper limbs to investigate the possible incidences of various types of communications between these two neighbouring peripheral nerves. RESULT: Twenty-eight per cent of limbs were found to have communication between these two nerves. When categorized according to Venieratos and Anagnostopoulou's classification method, 11 out of 14 cases (79%) showed type I communications, two out of 14 (14%) showed type II and the remaining one (7%) showed type III communication pattern. CONCLUSION: Prior knowledge of communications between these two neighbouring nerves, both in terms oftheir incidences and pattern ofcommunications, may be ofconsiderable significance to neurologists and orthopaedic surgeons in dealing with nerve entrapment syndromes in the upper limb of patients.

OBEJTIVOS: Las variaciones tales como las comunicaciones entre el nervio mediano y el nervio musculocutáneo o en su patrón de ramificación anormal constituyen un interés principal en el campo clínico y quirúrgico. El conocimiento de estas variaciones no sólo proporciona una interpretación adecuada del caso clínico, sino que también minimiza la complicación en abordajes quirúrgicos en esta región. MÉTODO: Se analizaron 50 miembros superiores aislados para investigar las posibles incidencias de diversos tipos de comunicaciones entre estos dos nervios periféricos vecinos. RESULTADO: Se halló que el veintiocho por ciento de los miembros tenía comunicación entre estos dos nervios. Cuando fueron categorizados según el método de clasificación de Venieratos y Anagnostopoulou, 11 de 14 casos (79%) mostró comunicaciones de tipo I, dos de 14 (14%) mostraron el tipo II, y el restante (7%) mostró un patrón de comunicación de tipo III. CONCLUSIÓN: El conocimiento previo de las comunicaciones entre estos dos nervios vecinos, en términos tanto de sus incidencias como patrones de comunicación, puede ser de una importancia considerable para los neurólogos y ortopédicos a la hora de tratar con el síndrome del atrapamiento del nervio en la extremidad superior de los pacientes.

A new anatomical variation of the musculocutaneous and the median nerve anastomosis.

Variations of the brachial plexus and its terminal branches are not uncommon.Therein, the anatomical variations of the musculocutaneous and the median nerve are classified into 5 types, while the communicating branches between the musculocutaneous and the median nerve are classified into 3 types, depending on their position related to the coracobrachial muscle. The case reviewed in this paper presents a variation similar to that of the second variety, but is significantly different due to the appearance of the proximal musculocutaneous nerve and its communicating branching, the site rising from the communicating branch (through the coracobrachial), and important clinical implications of this new variation. Despite the communicating branch being located in the upper third of the upper arm, it should not be considered as being a double lateral root of the median nerve.

A variation of the cords of the brachial plexus on the right and a communication between the musculocutaneous and median nerves on the left upper limb: a unique case.

During routine anatomical dissection of the upper extremity of a 64-year-old cadaver for educational purposes, we observed variations in the brachial plexus on each side. On the right an anomaly of cord formation was present and on the left there was a communication between the musculocutaneous nerve (MCN) and median nerve (MN). On the right side the brachial plexus showed two trunks, superior (C5 and C6) and inferior (C7, C8, and T1); the middle trunk was absent. The superior trunk bifurcated into anterior and posterior divisions, the anterior division continued as the lateral cord forming the MCN. The posterior division gave off the subscapular branch. The inferior trunk trifurcated into radial, median, and ulnar nerves. The radial nerve gave off the axillary and thoracodorsal nerves. The ulnar nerve gave off the median cutaneous nerves of the arm and forearm. The median nerve received a small ascending branch from the MCN. On the right side, there was a communicating branch from the MCN to the MN in the lower third of the arm region. This communicating branch also gave rise to a muscular branch to the brachialis muscle and the lateral cutaneous nerve of forearm. No additional heads of the biceps brachii muscle were observed in either upper limb. Knowledge of the variations of the brachial plexus in humans can be valuable for operations of the shoulder joint and its repair for providing an effective block or treatment for anesthetists and also for explaining otherwise incomprehensible clinical signs for neurologists.

Bilateral variations of musculocutaneous nerves with rare pattern in a Korean female cadaver.

Bilateral variations in the formation and branching of brachial plexus are rare. Variations between median and musculocutaneous nerves were observed on both sides during the dissection of an 87-year-old Korean female cadaver, whose cause of death was cholangiocarcinoma. The variations found were bilateral, in which each musculocutaneous nerve did not pierce the coracobrachialis muscle. The musculocutaneous nerve was rudimentary in the right arm and all branches arose from the median nerve separately, which corresponds to previous classification type 0-2. In the case of the left arm, the musculocutaneous nerve originated from the lateral cord, but had connections between median and musculocutaneous nerves below the coracobrachialis muscle, which corresponds to previous classification type 1-B-2. To the best of our knowledge, the bilateral variations between median and musculocutaneous nerves in this case have different features from other previous reports. Awareness of the possible variations between median and musculocutaneous nerves is important to both anatomists and clinicians.

Absence of musculocutaneous nerve with variations in course and distribution of the median nerve.

Variations in the brachial plexus and its terminal branches are not uncommon. A communicating branch arising from the musculocutaneous nerve to the median nerve is a frequent variation, but complete merging of musculocutaneous nerve into the median nerve is very rare. Here, we observed variations in the origin, course and distribution of the median nerve in the left upper limb. The musculocutaneous nerve was absent. The median nerve was formed in the upper part of the arm, in front of the brachial artery. The median nerve supplied the biceps, coracobrachialis and brachialis muscles and gave the lateral cutaneous nerve of the forearm. The present report provides evidence of variation in important nerves of the anterior compartment of the arm.

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.

Accessory coracobrachialis: a case report with its morphological and clinical significance.

METHOD: During the routine dissection of a male cadaver for teaching undergraduate medical students, a variation was seen in the morphology of coracobrachialis muscle. RESULTS: The presence of an anomalous head of coracobrachialis muscle which had muscular origin from an abnormal site on coracoid process and thin tendinous insertion at the junction of brachialis and triceps muscle in common with insertion of coracobrachialis muscle to the medial surface of the middle of the shaft of the humerus. CONCLUSION: Coracobrachialis muscle can have variant origin related to its embryogenesis with its clinical and surgical significance.