A 35-year-old male presents to the orthopaedic clinic with inability to walk normally after a motor vehicle accident. He has a fracture of the fibular neck on the right side. On examination, he cannot dorsiflex his right foot and walks with a characteristic high-stepping gait, dragging his toes. The structure marked **B** in the diagram is most likely injured. Which of the following clinical findings would you NOT expect in this patient?

Explanation

## Why "Loss of plantarflexion and sensation over the sole of the foot" is correct The structure marked **B** is the common peroneal (fibular) nerve, which is the most commonly injured nerve in the lower limb due to its superficial course around the fibular neck. Injury to this nerve results in foot drop due to loss of dorsiflexion (deep peroneal branch supplies tibialis anterior, extensor hallucis longus, and extensor digitorum longus) and loss of eversion (superficial peroneal branch supplies peroneus longus and brevis). Sensory loss occurs over the dorsum of the foot and lateral leg. Loss of plantarflexion and sensation over the sole of the foot are features of **tibial nerve injury**, which is much rarer and not the nerve injured in fibular neck fracture. Therefore, this finding would NOT be expected in common peroneal nerve injury. ## Why each distractor is wrong - **Loss of sensation over the dorsum of the foot and lateral aspect of the leg**: This is a classic sensory manifestation of common peroneal nerve injury and would definitely be present. - **Inability to evert the foot**: The superficial peroneal nerve (branch of common peroneal) innervates peroneus longus and brevis, which are the primary evertors. Loss of eversion is expected in common peroneal nerve injury. - **Foot drop with ankle inversion deformity**: This is the hallmark motor presentation of common peroneal nerve injury—foot drop from loss of dorsiflexion and unopposed action of invertors (tibialis posterior) leads to ankle inversion. This would definitely be present. **High-Yield:** Common peroneal nerve injury at the fibular neck → foot drop + high-stepping gait + ankle inversion + sensory loss over dorsum and lateral leg. Tibial nerve injury (rare) → loss of plantarflexion + sole sensation loss. [cite: Gray's Anatomy 42e Ch 81; Bailey & Love 28e]