The upper (superior) subscapular nerve is the first branch of the posterior cord of the brachial plexus.

The axons which form the upper subscapular nerve travel from the ventral rami of C5 and C6.

[1] The axons then branch from the posterior cord and form the upper subscapular nerve.

[1][2] The upper subscapular nerve innervates the superior portion of the subscapularis muscle.

[2][3] A lesion to the upper subscapular nerve can cause a reduced ability to medially rotate at the shoulder joint, however this function is supplemented by other muscles.