The musculocutaneous nerve in the arm is formed by splitting the brachial plexus at the inside border of the pectoral muscles into two branches. These branches continue to split as they run down through the upper arm, forearm, and into the wrist and hand. In the leg, the superficial peroneal nerve (also called musculocutaneous nerve) passes between the peronei and the extensor digitorum longus, piercesmycontentbreak the deep tissues of the lower third of the leg, and divides into a medial and intermediate dorsal cutaneous nerve.