## **Core Concept**
An ankle block is a regional anesthesia technique used to provide analgesia for procedures involving the foot and ankle. It involves blocking several nerves that innervate the ankle and foot. The nerves commonly blocked in an ankle block include the **tibial nerve**, **superficial peroneal nerve**, **deep peroneal nerve**, and **sural nerve**.

## **Why the Correct Answer is Right**
The correct answer, **saphenous nerve**, is not typically blocked in a standard ankle block. The saphenous nerve provides sensory innervation to the medial aspect of the leg and foot but is usually not included in the ankle block because its distribution is more proximal and its blockade might not be necessary for procedures limited to the foot and ankle. The other nerves listed are commonly targeted in an ankle block.

## **Why Each Wrong Option is Incorrect**
- **Option A:** The **tibial nerve** is indeed blocked in an ankle block as it provides sensation to the sole of the foot and motor innervation to the muscles of the foot.
- **Option B:** The **deep peroneal nerve** is blocked as it supplies the muscles and skin of the first web space of the foot.
- **Option C:** The **superficial peroneal nerve** is also blocked as it provides sensory innervation to the lateral lower leg and the dorsum of the foot.
- **Option D:** The **sural nerve** is blocked as it provides sensory innervation to the posterior lateral aspect of the leg and the lateral side of the foot.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the **saphenous nerve**, which is derived from the femoral nerve, often requires a separate block if anesthesia is needed for procedures on the medial foot or ankle, as it is not covered by a standard ankle block.

## **Correct Answer:** . saphenous nerve