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Introduction Variations in the formation and in the branching pattern of the brachial plexus are common. Numerous anastomotic variations between the musculocutaneous nerve (MCN) and the median nerve (MN) have been reported and could be implicated in a wide range of sensory and motor dysfunctions. Objective To report an uncommon case of an anastomotic variation between the MN and the MCN with a rare absence of the lateral cutaneous nerve of forearm (LCNF). Material and Methods A dissection of a male cadaver was performed at the Morphology Department of the Universidade Federal do Ceará, Fortaleza, state of Ceará, Brazil. The brachial plexus was exposed. Results It was observed that the MCN, after its origin in the lateral fasciculus of the brachial plexus, anastomoses with the MN in the middle third of the arm. It diverges from themost prevalent anatomical pattern, inwhich theMCNcontinues to passdistallybeneath the brachii biceps, originating the LCNF. In this case, the MCN does not emit its main terminal branch, the LCNF, which innervates the lateral portion of the skin of the forearm. In the present case, the innervation of the lateral portion of the skin of the forearmis provided by radial nerve branches. The reported case has practical implications, since the absence of the LCNF could cause hypoesthesia in the skin of the forearm. Conclusion Thus, the knowledge of the formation and of the branching pattern of the brachial plexus is clinically important for the correct clinical interpretation of the sensory and motor disorders of the upper limbs caused by peripheral nerve injuries, as well as for planning surgical procedures to correct upper limb traumas. [ABSTRACT FROM AUTHOR]

The extensor carpi radialis longus muscle (ECRLm) is located in the posterior compartment (extensorsupinator) of the forearm and has great importance in the closure of the hand. There are few biometric studies with respect to the point of origin of their branches of innervation, as well as on the distribution of them. For this study, 30 upper limbs, formalized, of Brazilian adult individuals were used, from the Faculty of Medicine of the Universidad Estadual de Ciencias da Saúde de Alagoas, Maceió, Brazil. After locating the nerve, we measured the distance between the origin of the primary branch and that of the motor points with respect to biepicondilar line (BEl), which were visualized and dissected using a magnifying glass. The nerve in question was observed at the level of the arm or proximal to BEl in 28 cases (93 %) and the remaining 2 at the level of this line (7 %). The branches for the ECRLm originated from the radial nerve, observing a primary branch in 20 limbs (80 %), and in the remaining 10 (20 %) two primary branches were observed, averaging 1.3 branches (SD 0.5). The most proximal origin of the first primary branch (PB) independent of whether there was 1 or 2 was on average 3 cm (SD 1.0) proximal to BEl. The most distal MP was distal to BEl in 24 cases with an average of 1.9 cm (SD 1.0); location at the BEl level in 3 cases. Only in 3 cases was the most distal MP found proximal to BEl, an average of 0.8 cm (SD 0.5). The distribution of motor points was variable, since many times the PB bifurcated into secondary branches and these, in turn, could divide up to 6 times in tertiary branches that penetrated in the muscle. The biometric knowledge of the origin of the nerve of the ECRLm, as well as its distribution, is an important contribution to the anatomo-surgical area, as well as its use in nerve blocks, nerve transfers and electrode placement areas for purposes of electrical stimulation in patients they need to rehabilitate the action of injured radial extensor musculature. [ABSTRACT FROM AUTHOR]