Prolonged compression of the lower leg typically injures which nerve, leading to dorsiflexion weakness?

• A. Deep peroneal nerve
• B. Tibial nerve
• C. Sural nerve
• D. Femoral nerve

Answer: (A)

Dorsiflexion is mainly performed by the anterior compartment of the leg, especially the tibialis anterior, along with other dorsiflexors that receive motor input from the deep peroneal (deep fibular) nerve. When this nerve is compressed, these muscles lose strength, leading to weakness in lifting the front of the foot—commonly seen as foot drop. The deep peroneal nerve also provides sensation in a small area between the first and second toes, which can help in clinical testing.

The tibial nerve controls the posterior compartment muscles responsible for plantarflexion; injuring it would weaken pushing the foot downward, not lifting it. The sural nerve is sensory and does not drive dorsiflexion. The femoral nerve innervates the quadriceps and other hip/knee muscles, so its injury would affect knee extension and hip flexion rather than dorsiflexion.