A 38-year-old man presents with weakness of ankle dorsiflexion and foot eversion, with sensory loss over the dorsum of the foot and lateral leg. All of the following branches of the common fibular nerve are affected EXCEPT:

Explanation

## Common Fibular Nerve Injury: Clinical Presentation and Branches ### Clinical Scenario Analysis The patient presents with: - **Motor deficit:** Weakness of ankle dorsiflexion and foot eversion - **Sensory deficit:** Loss over dorsum of foot and lateral leg This pattern is consistent with **common fibular nerve injury** at or above the fibular neck. ### Branches of the Common Fibular Nerve ```mermaid flowchart TD A[Common Fibular Nerve]:::outcome --> B[Superficial Fibular Nerve]:::action A --> C[Deep Fibular Nerve]:::action A --> D[Lateral Sural Cutaneous Nerve]:::action A --> E[Recurrent Articular Branch]:::action B --> B1[Motor: Fibularis longus & brevis<br/>Eversion of foot] B --> B2[Sensory: Lateral leg & dorsum foot] C --> C1[Motor: Tibialis anterior, EHL, EDL<br/>Dorsiflexion] C --> C2[Sensory: First web space] D --> D2[Sensory: Lateral leg] E --> E1[Articular innervation<br/>Knee joint] ``` **Key Point:** The **sural nerve** is a branch of the **tibial nerve**, NOT the common fibular nerve. It arises from the tibial nerve and carries sensory fibers from the lateral leg and lateral foot. ### Affected Branches in This Case | Branch | Motor Function | Sensory Distribution | Status in Case | |--------|----------------|----------------------|----------------| | **Deep fibular** | Dorsiflexion (tibialis anterior, EHL, EDL) | First web space | ✓ Affected | | **Superficial fibular** | Eversion (fibularis longus & brevis) | Lateral leg & dorsum foot | ✓ Affected | | **Lateral sural cutaneous** | — | Lateral leg | ✓ Affected | | **Recurrent articular** | — | Knee joint | ✓ Affected | | **Sural nerve** | — | Lateral leg & foot | ✗ NOT affected (tibial nerve branch) | **High-Yield:** The **sural nerve** is derived from the **tibial nerve** (with a communicating branch from the common fibular nerve in some individuals), but it is anatomically distinct and is NOT a direct branch of the common fibular nerve proper. **Clinical Pearl:** Common fibular nerve injury at the fibular neck is the most common lower limb nerve injury, often caused by prolonged pressure, tight casts, or knee dislocation. Patients present with **foot drop** and inability to dorsiflex or evert the foot.