Which of the following are features of common peroneal nerve injury?1. Inversion inability2. Loss of sensation of sole3. Foot drop4. Loss of extension of great toe5. Seen in fibular neck fracture
The question lists five features: inversion inability, loss of sensation of the sole, foot drop, loss of extension of the great toe, and seen in fibular neck fracture. I need to determine which of these are correct.
Starting with inversion inability. Wait, inversion is the movement where the sole turns inward. The muscles that invert the foot are the tibialis posterior, flexor hallucis longus, and flexor digitorum longus. These are innervated by the tibial nerve, not the peroneal. The peroneal nerve actually innervates the peroneus muscles which evert the foot. So inversion inability would not be a feature of peroneal nerve injury. So option 1 is incorrect.
Loss of sensation of the sole. The tibial nerve provides sensory innervation to the sole. The peroneal nerve supplies the dorsum of the foot. So loss of sensation on the sole would be due to tibial nerve injury, not peroneal. So option 2 is incorrect.
Foot drop. That makes sense. The peroneal nerve innervates the muscles that dorsiflex the foot (like the tibialis anterior) and evert it. If the nerve is injured, these muscles can't work, leading to foot drop. So option 3 is correct.
Loss of extension of the great toe. The extensor hallucis longus is innervated by the deep peroneal nerve, which is a branch of the common peroneal nerve. So if the common peroneal nerve is injured, this muscle would be affected, leading to inability to extend the great toe. So option 4 is correct.
Fibular neck fracture. The common peroneal nerve wraps around the fibular neck, so a fracture here can compress or damage the nerve. So option 5 is correct.
Putting it all together: the correct features are 3, 4, 5. Now looking at the options given (A-D), the correct answer would be the one that includes these. Since the options aren't provided, but the user says the correct answer is C, I can assume that in the original options, C includes 3,4,5. But I need to check each option's correctness based on the explanation.
**Core Concept**
The common peroneal nerve (a branch of the sciatic nerve) innervates the anterior and lateral leg muscles (responsible for dorsiflexion and eversion) and the lateral foot (sensory). Injury disrupts these functions, leading to foot drop and sensory deficits. It is vulnerable at the fibular head due to its superficial course.
**Why the Correct Answer is Right**
Common peroneal nerve injury causes:
1. **Foot drop** (loss of dorsiflexion from tibialis anterior weakness).
2. **Loss of great toe extension** (extensor hallucis longus, deep peroneal nerve branch).
3. **Fibular neck fractures**