Fascial Border Absence Between the Extensor Carpi Radialis Longus and Brachioradialis Muscles

Ultrasound (US) guidance may ensure proper needle placement during electromyography (EMG) when assessing for suitable donor muscles for upper limb reconstruction. A distinct intermuscular fascial border aids in delineating the separation between the brachioradialis (BR) and extensor carpi radialis longus (ECRL) muscles. However, this border may be absent, making correct needle placement complex and assessment more difficult. The purpose of this study was to describe the presence and absence of this fascial border in healthy individuals to help with accurate EMG needle placement.

Twenty healthy patients underwent sonographic examination by a single sonographer physician of the ECRL and BR to identify the presence or absence of the intermuscular fascial border.

The fascial border that routinely separates the ECRL and BR was absent in at least one arm in 20% of subjects (12.5% of upper limbs). One subject had an absent fascial border in both upper limbs.

US can assess for the presence or absence of intermuscular fascial borders. This assessment is important for accurate EMG needle placement and localization. While the clinical significance of an absent ECRL-BR fascial border is currently unknown, future studies should examine the effect of absent ECRL-BR fascial borders on wrist extension.