Clinicoembryological Submission of Unusual Variation in Course and Branching Pattern of Lateral Cord of Brachial Plexus – A Case Report

Variations are commonly observed and being reported in the formation of lateral cord of brachial plexus and in the communicationof branches of lateral cord of brachial plexus, but formation of median nerve by lateral root of median nerve from lateral cord andmedial root of median nerve from medial cord at a substantially low level is quite unusual and the case reports regarding piercingof the coracobrachialis by lateral cord of brachial plexus are infrequent. The present case report describes an unusual unilateralcourse of lateral cord piercing the coracobrachialis and ensuing path followed by its various branches as well as unusuallylow-level formation of median nerve from lateral and medial roots coming from the lateral and medial cord of brachial plexus,respectively. This was witnessed in the infraclavicular part of the brachial plexus during the routine gross anatomy dissectionof the left upper extremity in a 35-year-old Indian male cadaver. Since axilla and upper half of the arm are challenging areasfor surgical procedures, so the unusual variations being reported in this case may help the surgeons of different specialties inexploration of neuronal tumor, shoulder reconstructive surgery shoulder arthroscopy, and using the coracobrachialis flap fordifferent surgical purposes.

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.

Nerve Entrapment In The Osseoaponeurotic Tunnel Mimicking Struther’s Ligament Associated With Superficial Brachial Artery: An Embryological Error

Introduction: Coracobrachialis muscle is well known for its morphological variations. Anatomical variation ofcoracobrachialis near its insertion can cause compression of median nerve and brachial artery by mimickingstruther’s ligament. Our aim of the study was to examine and record the variations in origin and insertion ofcoracobrachialis muscle and to see their relationship with the median nerve and brachial artery.Methodology: During routine dissection for undergraduate students in KFMSR, 64 upper limbs were dissectedand observed for any variations in origin and insertion of Coracobrachialis muscle.Results: Of the 64 upper limbs dissected, we noted that in one cadaver, there were two heads of origin forcoracobrachialis muscle and there was also a variation in the insertion as abnormal slips, which were attachedto antebrachial fascia. The blood supply to this muscle was from the muscular branches of superficial brachialartery.Conclusion: The knowledge of this type of variations is important for surgeons, radiologists, neurologists andphysiotherapists for proper decision making during surgical considerations and injuries around elbow joint.Neurovascular structures like median nerve and superficial brachial artery may be compressed by the abnormalslips of coracobrachialis close to insertion.

A Morphological Study on the Anatomic Variation of the Musculocutaneous Nerve with its Clinical Implication.

Background: During surgery of the shoulder region the identification of musculocutaneous nerve (MCN) and its variation is important because it is vulnerable to injury from surgical instruments. The MCN is formed as the continuation of lateral cord of brachial plexus. The MCN travels obliquely below the coracoid process and enters the coracobrachialis (CB) muscle. The MCN supplies the muscles of front of arm, namely the CB, the Biceps brachii and Brachialis muscles. Methods: The Morphological study included 25 cadavers aged between 21 to 70 years. Both the right and the left upper limbs of each cadaver, 50 limbs were studied and documented. The MCN showed variations in their course, branching pattern and communication with MN (median nerve). Results: The lateral cord gives a direct branch to CB, then pierces the muscle in 2 cases (8%) unilaterally. MCN does not pierce the CB but communicates with median nerve in 3 cases (12%) unilaterally, whereas communication between MCN and MN seen in 5 cases (20%). Conclusion: The Knowledge of Variation in origin, course, branching pattern, termination and communication of MCN in the arm have the significance in shoulder injuries and reconstructive surgeries.

Topographic and biometric study of radial nerve branches to the muscles of the anterior compartment of the arm / Estudio topográfico y biométrico de los ramos del nervio radial para los músculos del compartimiento anterior del brazo

The radial nerve is a terminal branch of the brachial plexus that innervates the entire posterior compartment of the upper limb. Researches have shown that the branches can contribute to innervation of the muscles from the anterior compartment of the arm. This study sought to identify branches of radial nerve for brachialis and coracobrachialis muscles and its clinical value during surgery. Dissection was performed in 60 arms, from 30 corpses selected from the Human Anatomy Laboratories of Universidade Estadual de Ciências da Saúde de Alagoas (UNCISAL). In each arm, three segments of the same proportion were considered (proximal, middle and distal) in order to observe the number of radial nerve branches to brachialis and coracobrachialis muscles. Branches were identified in 4 of the 60 upper limb (6.66%) with the following distribution: nerve with 1 branch to the brachialis muscle in the distal third (1.66%); with 1 branch to the middle third of the coracobrachialis (1.66%) and 5 branches to the coracobrachialis muscle in the proximal third; 1 branch being found in an upper limb (1.66 %) and 4 branches in the other upper limb (1.66 %). The event was not bilaterally in the same body, and in four cases there was no branching, but only communication with other terminal nerves of the brachial plexus. In conclusion, although most authors do not describe the possibility of the occurrence of radial nerve branches to the muscles of the anterior compartment of the arm, this condition exists as an anatomical variation.

El nervio radial es un ramo terminal del plexo braquial que inerva el compartimiento posterior del miembro superior. Diversos estudios han mostrado que sus ramos pueden contribuir a la inervación de los músculos del compartimiento anterior del brazo. El presente estudio tuvo como objetivo identificar ramos del nervio radial dirigidos a los músculos braquial y coracobraquial y su importancia clínica durante las cirugías. Para ello, se disecaron 60 brazos de 30 cuerpos formolizados en los Laboratorios de Anatomía Humana de la Universidad Estadual de Ciencias de la Salud de Alagoas, Brasil (UNCISAL). En cada brazo, se consideraron tres partes de similares proporciones (proximal, medio y distal) para localizar los ramos dirigidos a los músculos mencionados. En 4 de los 60 brazos (6,66%) se identificaron ramos con la siguiente distribución: un ramo para el músculo braquial en el tercio distal (1,66%); un ramo para el tercio medio del músculo coracobraquial (1,66%) y cinco ramos para este mismo músculo en su tercio proximal; en otro miembro (1,66%)se encontró solo un ramo y en la otra muestra (1,66%) se encontraron cuatro ramos. Ninguno de los casos fue bilateral y en los cuatro casos no había ninguna ramificación. No hubo comunicación con el nervio musculocutáneo pero si con otros ramos del plexo braquial. Aunque la mayoría de los autores no describe la posibilidad de que el nervio radial inerve a los músculos anteriores del brazo, esta disposición existe como una variación anatómica.

Bilateral variation in Branching of Axillary Artery.

Bilateral variations in the branching pattern of axillary artery were seen in a 78 year male cadaver during routine dissection. On the right side superior thoracic artery was a branch of second part of axillary artery. Additional pectoral branches were seen coming out of the second part on either side. Bilaterally from the second part a common trunk originated which gave rise to lateral thoracic and subscapular artery. On the left side an additional pectoral branch from the common trunk was present. From the third part on either side a muscular branch supplied the coracobrachialis muscle. On the right side from the third part of axillary artery a common trunk started and divided into anterior and posterior circumflex humeral arteries.

Incidence of Third Head of Biceps Brachii in Indian Population.

Background: The biceps brachii is one of the muscles of the anterior compartment of the upper arm. It is characteristically described as a two-headed muscle that originates proximally by a long head and a short head. The present study was carried out to find the occurrence of a third head of biceps brachii among a sample Indian population. Materials and Methods: The arms of 35 adult cadavers were dissected and observed for variations in the origin and insertion of biceps brachii muscle bilaterally. Results: Among the 70 arms studied, three had 3-headed biceps brachii, 2 on the left and 1 on the right side. All the third heads were of humeral origin, which inserted into the radial tuberosity by a common tendon with the long and short heads. Conclusion: Knowledge of the existence of the third head of biceps brachii may enhance pre-operative evaluation, facilitate surgical intervention within the arm and improve postoperative outcomes.

Bilateral Pectoralis Minor Muscle Variant: A Case Report.

During a routine anatomical dissection we discovered an aberrant muscle slip associated with the pectoralis minor muscle that occurred bilaterally. The muscle slips originated from ribs five or six and inserted into the tendon of the coracobrachialis in close proximity the coracoid process of the scapula. Fibers of the muscle slip also blended with the pectoralis minor muscle on its lateral border. The muscle slips were innervated by the medial pectoral nerve. Reports and documentation of anatomical variants such as this provide an important resource for both researchers and clinicians.

Variation in the termination of musculocutaneous nerve

A variation of the musculocutaneous nerve was observed during routine dissection for first year medical students, in a 67 year old embalmed male cadaver. The termination of musculocutaneous nerve in left upper limb was variable. After piercing the coracobrachialis muscle, musculocutaneous nerve divided into lateral cutaneous nerve of the forearm and gave an accessory branch that joined with median nerve, lateral to the insertion of the coracobrachialis muscle. Knowledge of these variations is of great importance to surgeons and orthopaedicians who do surgical interventions in that region.

Incidence of Third Head of Biceps Brachii in South Indian Population

Additional heads of the biceps brachii muscle of arm have the clinical importance, because they mislead the surgeon in arm surgical procedures. Existence of such variation is one of the reasons for neurovascular compression in the arm region. The present study was conducted to find out the incidence of third head of biceps brachii among 80 samples in South Indian population. The third head of biceps brachii was found in right side in one case which was 13.7 cm in length and arising from antero medial wall of lower part of shaft of humerus. Incidence of the study is 1.25% in South Indians. Occurrence of supernumerary third head of biceps is rare in Indian population.

Bilateral Supernumerary Heads of Biceps Brachii.

The Biceps brachii is a muscle of flexor compartment of the arm. The biceps brachii muscle shows variation in the number of heads, with an estimated 9–22% of all people having a supernumerary head. Themost common variation is third head, but four, five, or even seven heads have been reported. Although supernumerary heads of the biceps brachii muscle have been frequently reported, bilateral asymmetric occurrence of supernumerary heads is relatively rare. During a routine cadaveric dissection at the Department of Anatomy, National Medical College, Birgunj, Nepal, we encountered bilateral supernumerary heads of the biceps brachii muscle; Three heads on the right arm and four heads on the left arm in a 68 year old male cadaver. These additional heads were supplied by branches from the musculocutaneous nerve. No additional anomalies were found on the remainder of both upper limbs of the same cadaver. It may cause compression of surrounding neurovascular structures or itmay lead to variation of normalmechanical actions and also can cause erroneous interpretation during routine surgeries.

A study on variation in the insertion of Coracobrachialis muscle and its clinical importance.

Background: The coracobrachialis muscle morphologically represents the adductor group of muscles in the arm but such function became insignificant in man during the process of evolution. It is more important morphologically than functionally & it is known for its morphological variations. Aims & Objective: Variations in the structures of the human body are of importance to clinicians while performing any surgery or procedure or in the diagnosis of certain clinical conditions. Our aim is to report the occurrence of variation in insertion of coracobrachialis muscle & to observe the relationship of its abnormal slip with the median nerve & brachial artery. Material and Methods: Present study was conducted on embalmed cadavers at various medical colleges in Gujarat. The coracobrachialis muscle was dissected in both the upper extremities & observed for any abnormal slip or for any variation in insertion. Results: A total of 120 upper limbs of 60 cadavers were dissected. Variation at insertion was found in four cadavers as an abnormal slip to medial epicondyle of humerus & to the deep fascia on the medial aspect of arm. [6.66 % , n = 60] Conclusion: Anomalous insertion of coracobrachialis muscle may lead to compression of median nerve & brachial artery. The knowledge of such variations are of importance for surgeons, orthopaedicians, neurologists, radiologists & physiotherapists while dealing with injuries or operations around elbow joint. This muscle can also be used in muscle transplants.

Bilateral absence of musculocutaneous nerve with unusual branching pattern of lateral cord and median nerve of brachial plexus / 대한해부학회지

A 43-year-old female cadaver showed a complete bilateral absence of the musculocutaneous nerve. The anterior compartment muscles of both arms were supplied by median nerve excepting the coracobrachialis which was innervated by a direct branch from the lateral cord of brachial plexus. The median nerve, after supplying the biceps and brachialis muscles, gave onto the lateral cutaneous nerve of the forearm. The median nerve also showed variation on the left side where it was formed by two lateral roots and one medial root. Variations of the brachial plexus are of great interest to anatomists, clinicians and surgeons, in that they may be incorporated in their day to day practice. Our present case may be noted for its clinical and surgical significance in the variations of brachial plexus which can be useful for diagnostic purposes.

Four-headed biceps brachii, three-headed coracobrachialis muscles associated with arterial and nervous anomalies in the upper limb / 대한해부학회지

A four-headed biceps brachii muscle and three-headed coracobrachialis muscle, high-originated radial artery and communication between the median and musculocutaneous nerves have been well documented in the available literature. However co-existence of these variations is rare. In this study we aimed to describe multiple variations in the upper limb and discuss their co-existence from clinical and embryological points of view.