Which nerve is indicated by sensation testing at the first dorsal web space of the hand?

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

Answer: (A)

The first dorsal web space is a region innervated by the superficial branch of the radial nerve, so testing sensation there directly assesses radial nerve function. This area lies on the dorsoradial side of the hand, distinguishing radial nerve territory from the other nerves: the median nerve covers the lateral palm and its palmar digits, the ulnar nerve covers the medial digits, and the axillary nerve supplies sensation over the lateral shoulder rather than the hand. If sensation is lost in that web space, it points to radial nerve involvement; preserved sensation there with other deficits would steer you toward median or ulnar issues.