**Core Concept**
The lateral aspect of the fibula is innervated by the deep fibular (peroneal) nerve, a branch of the common peroneal nerve. This nerve supplies motor function to the tibialis anterior, extensor digitorum longus, and extensor hallucis longus muscles, which are responsible for dorsiflexion of the ankle and extension of the toes.

**Why the Correct Answer is Right**
The deep fibular nerve exits the leg near the fibular head and runs along the lateral aspect of the fibula. Injury to this nerve disrupts motor innervation to the tibialis anterior and other dorsiflexors. As a result, the patient loses the ability to dorsiflex the ankle, leading to foot drop. This is a classic clinical sign of peroneal nerve palsy, especially when trauma occurs in the lateral fibular region.

**Why Each Wrong Option is Incorrect**
Option A: The lateral foot sensation is supplied by the sural nerve, not the deep fibular nerve. Thus, loss of sensation here is not a direct consequence of deep fibular injury.
Option B: Sensation of the first and second toes is primarily mediated by the saphenous nerve (a branch of the femoral nerve), not the deep fibular nerve. This area is not affected.
Option C: Inversion of the foot is controlled by the tibialis internus, which is innervated by the superficial fibular nerve (a branch of the common peroneal nerve). While related, the injury here primarily affects dorsiflexion, not inversion.

**Clinical Pearl / High-Yield Fact**
Foot drop due to peroneal nerve injury is a hallmark of lateral fibular trauma. Always assess for dorsiflexion deficit in patients with fibular injuries—this is a key diagnostic clue.

✓ Correct Answer: D. Loss of dorsiflexion