The common peroneal nerve is a branch of the sciatic nerve that runs down the leg. It is responsible for controlling the muscles that lift the foot and toes, as well as providing sensation to parts of the lower leg and the top of the foot. This nerve divides into two main branches: the superficial peroneal nerve and the deep peroneal nerve. Damage to the common peroneal nerve can lead to conditions such as foot drop, where a person has difficulty lifting the front part of the foot, affecting walking and balance.