Injury to the common fibular nerve would most disrupt which movement?

• A. Dorsiflexion
• B. Plantarflexion
• C. Hip Adduction
• D. Knee Extension

Answer: (A)

When the common fibular (peroneal) nerve is injured, the muscles that dorsiflex the foot are most affected. These muscles—primarily the tibialis anterior and the extensors on the front of the leg—lift the front of the foot up toward the shin. Losing their function leads to difficulty or inability to dorsiflex, producing foot drop. Other movements rely on different nerves: plantarflexion is controlled by the tibial nerve in the posterior compartment, hip adduction by nerves like the obturator, and knee extension by the femoral nerve. So the movement most disrupted by this injury is dorsiflexion.