Which nerve is a branch of a root of the brachial plexus?

The roots of the brachial plexus are the anterior rami of spinal nerves Cs-T1. These five roots form the three trunks of the plexus. Each trunk divides into an anterior and a posterior division. The divisions form the three cords of the brachial plexus. The dorsal scapular nerve is a branch of the C, root. The supra scapular nerve is a branch of the upper trunk. The upper subscapular nerve and the thoracodorsal (middle subscapular) nerve are branches of the posterior cord. The lateral pectoral nerve is a branch of the lateral cord.