The variable communicating branches between musculocutaneous and median nerves: a morphological study with clinical implications

Abstract

Abstract:Background: The course of the brachial plexus, its relations with surrounding structures and unique primary and secondary divisions result in its wide range of anatomical variations. Most of these variations were detected during anatomical dissections and studies. It has been found that 53% of studied brachial plexuses contained variations. The communication between musculocutaneous and median nerves is the most common variation of infraclavicular part of brachial plexus. Methods: During gross anatomical dissections of peripheral nerves, we observed neuronatomical variations in upper limbs of four formalin embalmed adult cadavers. Musculocutaneous and median nerves were connected by a communicating branch at distinct level in each cadaver. The formation and relations of both nerves were noted in each case to exclude the existence of other anatomical variations. The connections were measured and documented by digital camera. Results: The communicating fi bers of variations 1 and 2 were located in the upper third of arm and proximally to musculocutaneous nerve penetration through coracobrachialis muscle. In variations 3 and 4, the communicating branch was situated in the lower third of arm and distal to the nerve penetration point. Conclusion: Variable interconnections between musculocutaneous and median nerve have to be considered in diagnosis of nerve lesions in axillary and arm regions. Compound musculocutaneous and median nerve neuropathy would occur in lesions of the interconnecting branches. Injuries of musculocutaneous nerve proximal to these branches can cause particular and unexpected symptoms, such as weakness of forearm fl exors and thenar muscles (Fig. 6 The brachial plexus is formed by the anterior rami of the cervical nerves C5-C8. It receives variable connections from the anterior rami of the fourth cervical nerve (C4) and the fi rst thoracic nerve (T1). The prefi xed type of the plexus is characterized by thick contributive nerve fi bers from C4 and thin or absent fi bers from T1. In the constitution of the postfi xed brachial plexus the fi rst two thoracic nerves (T1-T2) with absence of the nerve connection from C4 take part. The prefi xation of the plexus is more common than its postfi xation (1, 2).The roots of the plexus lie in the posterior cervical triangle between the anterior and middle scalene muscles. The nerve roots unite to form complex nerve network, from which the three primary trunks of the brachial plexus are branching: superior middle and inferior trunks. These are passing together with the subclavian artery under the clavicle and through the scalene gap. Each trunk is divided into anterior and posterior divisions. The lateral, medial and posterior cords of the plexus are formed by these divisions in the axillary fossa. The cords are named according to their relative position around the axillary artery (3, 4).From the topographical point of view the plexus is divided into supraclavicular and infraclavicular parts. The supraclavicular part gives off branches to innervate th...

Origin and antimeric distribution of brachial plexus nerves in Macaca mulatta (Zimmermann, 1780) (Primates: Cercopithecidae)

“…The proximal communication between the musculocutaneous and median nerves has a close relationship with the axillary artery, whereas the distal branch is related to the brachial artery. These relationships may lead to compression of the arteries and effects on the blood supply to the limb (Fazan et al 2003;Deshmukh & Devershi 2006;El Falougy et al 2013).…”

BRACHIAL PLEXUS IN THE Leopardus geoffroyi

“…This is functionally important because it allows the continuity of stimulus conduction even after injury in one of these nerves (44) . This junction is described as a common variation among humans (45) , and Iwamoto et al (46) in their study considered the analysis of this communication of branches essential for comparative studies between mammals.…”

Brachial Plexus in the Pampas Fox (Lycalopex gymnocercus): a Descriptive and Comparative Analysis

“…This communicating branch also carries efferent fibers from musculocutaneous to median nerve to supply the paw (Kitchell et al, ). In humans, the presence of a communicating branch between these nerves is regarded as one of the most commons variations of brachial plexus (El Falougy et al, ). The studies of this specific variation in humans alerted for unusual clinical signs and caution during surgical approaches (Arques, ), mentioned ontogenetic and developmental aspects (Saeed and Rufai, ), claimed for comparative studies in mammals (Iwamoto et al, ), but didn't speculate functional advantages.…”