Hartmann's boutonnière: an anatomical study of digital neural loop penetrations in the palm

We found neural loop penetrations by digital arteries in 47 of 51 dissected palms. They were classified into four types according to morphology. The most frequent type was observed in the proper digital nerves of the second to fourth interdigital spaces just after branching from the common digital nerves. If neural loop penetrations are not carefully identified at operation they may be damaged and therefore it is important for hand surgeons to recognize the existence of these structures.