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Anatomic Variations of the Musculocutaneous Nerve and Clinical Implications for Restoration of Elbow Flexion

  • Praveen Bhardwaj
    Affiliations
    Department of Plastic, Hand and Microsurgery, Ganga Medical Centre & Hospital Pvt. Ltd., Coimbatore, India
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  • Hari Venkatramani
    Affiliations
    Department of Plastic, Hand and Microsurgery, Ganga Medical Centre & Hospital Pvt. Ltd., Coimbatore, India
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  • Brahman Sivakumar
    Affiliations
    Department of Hand and Peripheral Nerve Surgery, Royal North Shore Hospital, New South Wales, Australia

    Australian Research Collaboration on Hands, Mudgeeraba, Queensland, Australia

    Department of Orthopaedic Surgery, Hornsby Ku-ring-gai Hospital, Hornsby, New South Wales, Australia

    Department of Orthopaedic Surgery, Nepean Hospital, Kingswood, New South Wales, Australia

    Discipline of Surgery, Sydney Medical School, the Faculty of Medicine and Health, University of Sydney, Syndey, Australia
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  • David J. Graham
    Affiliations
    Australian Research Collaboration on Hands, Mudgeeraba, Queensland, Australia

    Discipline of Surgery, Sydney Medical School, the Faculty of Medicine and Health, University of Sydney, Syndey, Australia

    Department of Musculoskeletal Services, Gold Coast University Hospital, Southport, Queensland, Australia

    Discipline of Surgery, School of Medicine and Dentistry, Griffith University, Southport, Queensland, Australia

    Department of Orthopaedic Surgery, Queensland Children’s Hospital, South Brisbane, Queensland, Australia
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  • Varadharajan Vigneswaran
    Affiliations
    Department of Plastic, Hand and Microsurgery, Ganga Medical Centre & Hospital Pvt. Ltd., Coimbatore, India
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  • S. Raja Sabapathy
    Correspondence
    Corresponding author: S. Raja Sabapathy, MS, MCh, Ganga Hospital, 313 Mettupalayam Road, Coimbatore, Tamil Nadu, 641043, India
    Affiliations
    Department of Plastic, Hand and Microsurgery, Ganga Medical Centre & Hospital Pvt. Ltd., Coimbatore, India
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Published:September 02, 2022DOI:https://doi.org/10.1016/j.jhsa.2022.07.014

      Purpose

      The restoration of elbow flexion is of primary importance in the management of patients with brachial plexus injuries. Superior functional outcomes via fascicle transfer from the ulnar and median nerves have resulted in this transfer being considered the mainstay of recovery of elbow flexion in patients with intact C8 and T1 function. An understanding of the anatomy of the musculocutaneous nerve (MCN) and its branching pattern is key while performing these transfers.

      Methods

      A prospective cohort study was conducted in patients who underwent nerve transfer for the restoration of elbow flexion following a traumatic brachial plexus injury. The anatomic course and branching pattern of the MCN were recorded in eligible cases, both as a line diagram and using intraoperative photographs.

      Results

      One hundred fifty patients underwent nerve transfer for the restoration of elbow flexion following an injury to the brachial plexus. The MCN in 138 patients (92%) was found to pierce the coracobrachialis muscle before emerging lateral to it. One hundred thirty-four patients (89.3%) demonstrated the “classical” anatomy. One hundred fifteen patients (76.6%) had a single primary branch to the biceps, whereas 25 patients (16.6%) demonstrated a discrete motor branch to each head. One hundred thirty-three dissections (88.6%) revealed a single muscular branch to the brachialis arising posteromedially from the MCN, distal to the origin of the branch to the biceps brachii. Notable unreported variations, such as the MCN penetrating the biceps as it descended, multiple brachialis branches, and trifurcation of divisions of the MCN, were documented.

      Conclusions

      Variations in MCN anatomy are quite common, and even unreported variations can be encountered.

      Clinical relevance

      Exploration of the MCN and its branches for nerve transfers requires knowledge of these anatomic variations and vigilance to prevent inadvertent injuries while dissecting them for nerve transfer surgery.

      Key words

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