The anterior divisions of the upper and middle trunks unite to form the lateral cord . The anterior division of the lower trunk forms the medial cord. All 3 posterior divisions from each of the 3 cords all unite to form the posterior cord. The cords are named according to their position relative to the axillary artery. Terminal Branches are mixed nerves containing both sensory and motor axons.
Musculocutaneous nerve is derived from the lateral cord.
Axillary nerve is derived from the posterior cord. Motor innervation is deltoid and teres minor muscles that act on the shoulder joint. Sensory innervation is from the skin just below the point of the shoulder. Radial nerve is also derived from the posterior cord. Sensory innervation is from the skin on the dorsum of the hand on the radial side.