Anatomy and quantitation of the subscapular nerves.

Information regarding branches of the brachial plexus can be of utility to the surgeon for neurotization procedures following injury. Sixty-two adult cadaveric upper extremities were dissected and the subscapular nerves identified and measured. The upper subscapular nerve originated from the posterior cord in 97% of the cases and in 3% of the cases directly from the axillary nerve. The upper subscapular nerve originated as a single nerve in 90.3% of the cases, as two independent nerve trunks in 8% of the cases and as three independent nerve trunks in 1.6% of the cases. The thoracodorsal nerve originated from the posterior cord in 98.5% of the cases and in 1.5% of the cases directly from the proximal segment of the radial nerve. The thoracodorsal nerve always originated as a single nerve from the brachial plexus. The lower subscapular nerve originated from the posterior cord in 79% of the cases and in 21% of the cases directly from the proximal segment of the axillary nerve. The lower subscapular nerve originated as a single nerve in 93.6% of the cases and as two independent nerve trunks in 6.4% of the cases. The mean length of the lower subscapular nerve from its origin until it provided its branch into the subscapularis muscle was 3.5 cm and the mean distance from this branch until its termination into the teres major muscle was 6 cm. The mean diameter of this nerve was 1.9 mm. The mean length of the upper subscapular nerve from its origin to its termination into the subscapularis muscle was 5 cm and the mean diameter of the nerve was 2.3 mm. The mean length of the thoracodorsal nerve from its origin to its termination into the latissimus dorsi muscle was 13.7 cm. The mean diameter of this nerve was 2.6 mm. Our hopes are that these data will prove useful to the surgeon in surgical planning for potential neurotization procedures of the brachial plexus.