A 35-year-old patient has a small but painful tumour under the nail of the little finger. Which of the following nerves would have to be anaesthetized for a painless removal of the tumor?
## **Core Concept**
The question tests knowledge of the sensory innervation of the fingers and nails. The sensory innervation to the fingers is provided by the digital nerves, which are branches of the median and ulnar nerves.
## **Why the Correct Answer is Right**
The correct answer, , involves the dorsal digital nerve or the proper digital nerve. For a tumor under the nail of the little finger, anesthesia would be required for the nerve supplying the little finger. The little finger is innervated by the **ulnar nerve**, specifically through its **digital branches**. The ulnar nerve divides into the superficial and deep branches, and the superficial branch further divides into the dorsal and palmar cutaneous branches and the proper digital nerves. The proper digital nerve for the little finger arises from the ulnar nerve and provides sensory innervation.
## **Why Each Wrong Option is Incorrect**
* **Option A:** This option would be incorrect if it referred to a nerve not primarily responsible for the sensory innervation of the little finger. For example, if it referred to a branch of the median nerve, it would not be correct because the median nerve primarily supplies the thumb, index, middle finger, and the radial half of the ring finger.
* **Option B:** Similarly, this would be incorrect if it did not accurately represent the nerve responsible for the sensory innervation of the little finger.
* **Option D:** This option would be incorrect if it referred to a nerve with a different distribution, such as the radial nerve, which primarily supplies the back of the hand and the thumb.
## **Clinical Pearl / High-Yield Fact**
A useful clinical pearl to remember is that for procedures on the fingers, a **digital nerve block** can provide effective anesthesia. This involves injecting local anesthetic around the digital nerves, which run along the sides of the fingers. For the little finger, this would specifically involve blocking the **ulnar digital nerves**.
## **Correct Answer:** . **Ulnar Nerve**