Which nerve block is injected into the anatomical snuff box to anesthesia the lateral aspect of the proximal thumb?

• A. Radial
• B. Ulnar
• C. Median
• D. Pollus

Answer: (A)

The important idea is that the superficial branch of the radial nerve provides sensation to the dorsolateral (lateral) part of the proximal thumb. The anatomical snuff box is where this nerve runs just under the skin, next to the radial artery. Injecting local anesthetic here blocks those sensory fibers, producing anesthesia of the lateral proximal thumb without affecting the palm or other digits.

The ulnar and median nerves supply other regions of the hand, not the specific dorsoradial thumb area, so blocking them wouldn’t give the targeted numbness described. The term “Pollus” isn’t a nerve name, so it wouldn’t apply. Therefore, a radial nerve (superficial branch) block in the snuff box is the correct choice.