Innervation density of the base of the palm

Cutaneous nerves of the palm were localized and quantitated by longitudinal axis, proximity to the distal palmar crease, and tissue layer to identify an incision that would avoid injury to the palmar branches of cutaneous nerves. Cadaveric palms (n = 10) harvested en bloc were fixed at physiologic tension and prepared using the celloidin method and hematoxylin-eosin staining. The cutaneous nerves of the palm were counted and classified by their size and location within each tissue layer and longitudinal axis as well as by proximal, middle, and distal locations within each axis. The mean number of large nerves identified within regions of the palm differed by tissue layer and longitudinal axis but not by longitudinal location within axes. The long/ring finger web space was characterized by the lowest innervation density; the index/long finger web space and ring finger axis were characterized by the greatest innervation density. An incision in the long/ring finger web space 2 cm proximal to Kaplan's cardinal line should result in injury to fewer nerves and reduce the incidence of painful neuromas during open carpal tunnel release.