The innervation of the axillary arch determined by surface stimulodetection electromyography

Authors

  • Thyl Snoeck,

    1. Department of Anatomy, Morphology and Biomechanics – Haute Ecole Paul Henri Spaak, Brussels, Belgium
    2. Department of Occupational and Environmental Physiology – Haute Ecole Paul Henri Spaak, Brussels, Belgium
    3. Department of Experimental Anatomy – Vrije Universiteit Brussel, Brussels, Belgium
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    • T.S. and S.P. contributed equally to this work.

  • Costantino Balestra,

    1. Department of Anatomy, Morphology and Biomechanics – Haute Ecole Paul Henri Spaak, Brussels, Belgium
    2. Department of Occupational and Environmental Physiology – Haute Ecole Paul Henri Spaak, Brussels, Belgium
    3. Department of Experimental Anatomy – Vrije Universiteit Brussel, Brussels, Belgium
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  • Flore Calberson,

    1. Department of Anatomy, Morphology and Biomechanics – Haute Ecole Paul Henri Spaak, Brussels, Belgium
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  • Caroline Pouders,

    1. Department of Human Anatomy – Vrije Universiteit Brussel, Brussels, Belgium
    2. Department of Basis Medical Sciences – Universiteit Gent, Gent, Belgium
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  • Steven Provyn

    1. Department of Anatomy, Morphology and Biomechanics – Haute Ecole Paul Henri Spaak, Brussels, Belgium
    2. Department of Experimental Anatomy – Vrije Universiteit Brussel, Brussels, Belgium
    3. Department of Human Anatomy – Vrije Universiteit Brussel, Brussels, Belgium
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    • T.S. and S.P. contributed equally to this work.


Thyl Snoeck, PhD, Haute Ecole Paul Henri Spaak, Department of Anatomy, Morphology and Biomechanics, Avenue Charles Schaller, 91, 1160 Brussels, Belgium. E:snoeck@he-spaak.be

Abstract

The axillary arch (AA) is a muscular anatomical variation in the fossa axillaris that has been extensively studied in cadaveric specimens. Within these dissections, different innervations of the AA have been proposed, but this has never been explored in vivo. Knowledge of the innervation of the AA is required in order to better understand its function (e.g. predisposition for certain sports and/or activities, understanding shoulder injuries in overhead sports). Here, we report on the use of surface stimulodetection electromyography (SSEMG) to resolve the innervation of the AA in 20 subjects (12 women, eight men – mean age of 21.3 ± 2.7 years) with a uni- or bilateral AA. SSEMG of each muscle [M. latissimus dorsi (MLD) and M. pectoralis major] was performed with a four-channel electrostimulation measuring system in order to determine the innervation of the AA. The results showed co-contraction of the MLD in 85% of the subjects after AA stimulation. In the remaining subjects, no specific localized response was observed due to non-specific nerve stimulation, inherent to the proximity of the brachial plexus in these individuals. Our findings demonstrate that SSEMG exploration offers a practical and reliable tool for investigating anatomical aspects of muscle innervation in vivo. Using this approach, we conclude that the AA receives the same innervation as the MLD (the N. thoracodorsalis), and may be considered a muscular extension of the latter.

Ancillary