A 43-year-old man sustains a fracture of the tibia. There are no neurologic or muscular lesions noted on careful examination. An above-knee cast is applied. After 6 weeks, the plaster is removed. It is noted that he has a foot drop and is unable to extend his ankle because of pressure injury to which of the following?

The common fibula (peroneal) nerve divides into the superficial fibula (peroneal) nerve, which supplies the fibula (peroneal) compartment, and the deep fibula (peroneal) nerve, which supplies the extensor compartment of the leg. This injury may occur because of a fracture of the proximal fibula or because of compression of the nerve by a tightly applied plaster cast in this region.