Pigmented border as a new surface landmark for digital nerve blocks: a cross sectional anatomical study.

The purpose of this study was to identify surface anatomy of digital nerves in relation to the pigmented border of digits. Three-hundred and sixty digital nerves in 36 preserved adult cadaveric hands were dissected under magnification. The digital nerves were constantly located anterior to the pigmented border. The median curvilinear distance along the skin from the pigmented border to the digital nerves of the index, middle, ring and little fingers was 1.4 mm. In the thumb, this distance was 2.4 and 3.7 mm on the radial and ulnar sides, respectively. The digital nerve was located 2.4 mm deep to the skin in all fingers. The median angle to the nerve from the skin at the pigmented border was 30°. These dimensions differed in the thumb compared with the rest of the fingers. We conclude that the pigmented border of digits is a reliable anatomical landmark to locate digital nerves.