Complete Extremities Muscles Exam Practice 2026

When the common fibular nerve is injured at the fibular neck, the nerve is disrupted before it divides into the superficial and deep peroneal (fibular) branches. The deep branch controls dorsiflexion of the foot (tibialis anterior), so loss of this function leads to foot drop. The superficial branch controls eversion (peroneus longus and brevis), so eversion is lost as well. Because both branches are affected, sensory fibers to the dorsum of the foot are diminished or lost.

Plantarflexion, which is mainly mediated by the tibial nerve (gastrocnemius, soleus), is typically preserved, as is knee extension and thigh adduction, which are served by other nerves (femoral and obturator). Hence the presentation described—foot drop with loss of dorsiflexion and eversion and sensory loss on the dorsum of the foot—is the classic outcome of injury at the fibular neck.