Branches off the C5-C7 roots, descends posteriorly to the roots of the plexus and the axillary aery and along the lateral surface of the serratus anterior muscle, with the lateral thoracic aery, while supplying the muscle. Injury to the long thoracic nerve results in paralysis of the serratus anterior muscle. This presents with the medial border of the scapula sticking straight out of the back (winged scapula).