Variations in Subscapularis Muscle Innervation-A Report on Case Series

Area of Science:

• Anatomy
• Neuroscience

Background:

• The subscapularis muscle typically receives innervation from the upper and lower subscapular nerves, originating from the brachial plexus.
• Previous literature indicates significant variability in the innervation patterns of the subscapularis muscle.

Purpose of the Study:

• To investigate the frequency and characteristics of accessory subscapular nerves.
• To assess the anatomical variations in subscapular nerve branching.

Main Methods:

• Cadaveric dissection of 31 specimens.
• Assessment of accessory subscapular nerve frequency.
• Measurement of nerve insertion distances to the myotendinous junction.

Main Results:

• Accessory subscapular nerves were identified in 9.7% (3 out of 31) of the specimens.
• All identified accessory nerves originated from the posterior cord of the brachial plexus proximal to the thoracodorsal nerve, classifying them as accessory upper subscapular nerves.
• No accessory lower subscapular nerves were observed.

Conclusions:

• Accessory subscapular nerves are relatively common anatomical variations.
• These variations must be considered in surgical interventions, nerve blocks, and diagnostic imaging procedures involving the shoulder and brachial plexus.