The deep peroneal nerve makes up one section of the common peroneal nerve. The common peroneal nerve runs alongside the sciatic nerve, from the femur to the buttocks. It then courses further down on its own along the knee and behind the fibula. The nerve then splits inside the neck of the fibula into two parts: the deep peroneal nerve and the superficial peroneal nerve.
The superficial nerve simply sits closer to the skin than the deep nerve, but they each connect to different muscles and tissue. This means injury to one of the branches affects the body differently than an injury to the other.
The deep peroneal nerve is responsible for lifting up the toe and ankle. It also affects feeling in the skin between the big toe and second toe, but this is the only area of skin it affects. This means any injury to this nerve causes ankle and toe weakening along with numbness between the big toe and second toe. The superficial nerve, however, mainly affects the skin in the calf and on top of the foot.