Radial border of digits of hand

The radial border of the digits of the hand refers to the lateral (thumb-side) margin of each finger. Anatomically, "radial" designates the side of the digit that is oriented toward the radius bone, which is the lateral bone of the forearm in the anatomical position. For the thumb, the radial border is the lateral aspect; for the index, middle, ring, and little fingers, it is the side facing the thumb (i.e., the side closest to the radius when the hand is in the anatomical position).