Which of the following muscles is innervated by the common fibular nerve and is responsible for dorsiflexion of the foot?

Explanation

## Common Fibular Nerve Innervation ### Motor Supply of the Common Fibular Nerve **Key Point:** The common fibular nerve innervates muscles of the **anterior and lateral compartments of the leg**. The primary dorsiflexor is the **tibialis anterior**, which is the most important muscle for foot dorsiflexion. ### Anatomical Distribution **High-Yield:** The common fibular nerve divides into: 1. **Superficial fibular branch** → Fibularis longus and brevis (eversion) 2. **Deep fibular branch** → Tibialis anterior, extensor digitorum longus, extensor hallucis longus (dorsiflexion) ### Muscles Innervated by Common Fibular Nerve | Compartment | Muscle | Action | Nerve Branch | | --- | --- | --- | --- | | **Anterior** | Tibialis anterior | Dorsiflexion + inversion | Deep fibular | | **Anterior** | Extensor digitorum longus | Dorsiflexion + toe extension | Deep fibular | | **Anterior** | Extensor hallucis longus | Dorsiflexion + great toe extension | Deep fibular | | **Lateral** | Fibularis longus | Eversion + plantarflexion | Superficial fibular | | **Lateral** | Fibularis brevis | Eversion | Superficial fibular | ### Clinical Correlation **Clinical Pearl:** Common fibular nerve injury (e.g., at the fibular head from tight casts, prolonged crossing of legs, or trauma) results in **foot drop** — inability to dorsiflex the foot, causing a characteristic high-stepping gait. The patient cannot lift the toes during walking. **Mnemonic:** **DAB = Deep fibular = Anterior + Dorsiflexion/extension**; **SAB = Superficial fibular = Lateral + ABduction (eversion)** ### Contrast with Tibial Nerve **Warning:** Do not confuse with tibial nerve, which innervates: - Tibialis posterior (inversion + plantarflexion) - Soleus and gastrocnemius (plantarflexion) - Foot intrinsics