## **Core Concept**
The nail bed of the fingers receives its nerve supply from the digital nerves, which are branches of the median and ulnar nerves. Specifically, the nerve supply to the nail bed of the index finger is crucial for sensation.

## **Why the Correct Answer is Right**
The correct answer, **D. Lateral digital nerve of index finger**, is right because the lateral digital nerve, a branch of the median nerve, supplies the nail bed of the index finger. The median nerve divides into digital nerves that provide sensory innervation to the thumb, index, middle finger, and the radial half of the ring finger. The lateral digital nerve specifically innervates the index finger.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify a nerve that supplies the index finger's nail bed.
- **Option B:** This option is incorrect as it does not accurately represent the nerve supply to the nail bed of the index finger.
- **Option C:** This option is incorrect because, similar to option B, it does not accurately describe the nerve supply to the index finger's nail bed.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the nail bed is highly innervated with sensory nerve endings, making it very sensitive to pain. The digital nerves provide this sensory innervation, which is essential for the fine motor functions and sensory feedback of the fingers.

## **Correct Answer:** D. Lateral digital nerve of index finger.