Anatomy of Long Thoracic Nerve Innervation serratus anterior Origin long thoracic nerve is derived from ventral rami of C5, C6, C7 roots of brachial plexus C8 contribution in 8% of patients Course runs downward & pases anterior to scalenus posterior muscle courses distal and laterally deep to clavicle and superficial to first and second rib runs inferior on chest wall along mid axillary line on the outer surface of the serratus anterior for a distance of 22 to 24 cm Terminal Branches terminal branches are small branches of long thoracic nerve that penetrate into serratus anterior muscles Clinical Condition Scapular Winging