Which nerve block yields anesthesia to the lateral proximal thumb?

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

Answer: (A)

Nerve blocks work by interrupting the sensory signals carried by that specific nerve, so the skin area it normally supplies becomes numb. The radial nerve provides cutaneous sensation to the dorsolateral aspect of the hand, including the skin over the base and proximal part of the thumb on the dorsal side. Therefore, a radial nerve block will produce anesthesia in the lateral proximal thumb. The median nerve mainly covers the palmar surface of the thumb and the lateral three digits, the ulnar nerve the medial digits, and there isn’t a standard nerve named “Pollus” that would give a consistent numbness pattern.