A Cadaveric Study on the Variations in the Infraclavicular Part of Brachial Plexus in Axillary Region and Upper Arm

The brachial plexus shows frequent anatomical variations that can complicate diagnosis, surgical planning, and anesthetic procedures. Detailed knowledge of these variations is essential to prevent iatrogenic injury and improve clinical outcomes.

Eighteen donors (36 upper limbs) were dissected at Mercer School of Medicine, Columbus, Georgia, United States. The sample included 10 males and 8 females, aged 36-89 years (mean age: 67.67 years). Dissections followed Grant's Dissector, 17th edition, with all variations in the infraclavicular brachial plexus and its branches in the axillary region and upper arm documented, photographed, and measured.

Variations were found in 16 brachial plexuses (44.4%) from nine donors. In total, 32 variations were identified, involving the medial and posterior cords, median, musculocutaneous, ulnar, radial, axillary, lower subscapular, and thoracodorsal nerves. Bilateral variations were more common (77.8%) than unilateral ones (22.2%), often with two to three variants on one side. Several rare or previously undescribed findings were noted, including a median nerve with an accessory lateral root located between the main and aberrant axillary arteries, a rare communication between the medial cord and lateral root of the median nerve, a rare communication between the ulnar and median nerves in the upper arm, bifurcation of the musculocutaneous nerve, trifurcation of the radial nerve, trifurcation of the axillary nerve, posterior division of the axillary nerve passing through the triangular space, posterior division of the axillary nerve supplying both teres minor and teres major, bifurcated axillary nerve accompanied by an accessory subscapularis muscle, accessory thoracodorsal nerve arising from the axillary nerve, and quadfurcation of the posterior cord.

Contrary to previous literature, axillary nerve variations were the most common. Bilateral deviations were frequent, often associated with arterial variations. Multiple rare and undescribed patterns identified in this study expand current knowledge of infraclavicular brachial plexus anatomy.