Background and objectives: The subscapularis muscle is typically innervated by two distinct nerve branches, namely the upper and lower subscapular nerve. These usually originate from the posterior cord of the brachial plexus. A large number of variations have been described in previous literature. Materials and Methods: Dissection was carried out in 31 cadaveric specimens. The frequency of accessory subscapular nerves was assessed and the distance from the insertion points of these nerves to the myotendinous junction was measured. Results: Accessory subscapular nerves were found in three cases (9.7%). According to their origin from the posterior cord of the brachial plexus proximal to the thoracodorsal nerve all three nerves were identified as accessory upper subscapular nerves. No accessory lower subscapular nerves were found. Conclusion: Accessory nerves occur rather commonly and need to be considered during surgery, nerve blocks, and imaging procedures.
Keywords: anatomical variation; lower subscapular nerve; muscle innervation; subscapularis; upper subscapular nerve.