The importance of internal anatomy of the peripheral nerves to nerve repair in the forearm and hand.

We have completed and analyzed recent studies on the internal topography of the median and ulnar nerves of the forearm and hand. These findings have been compared with the classic studies of Sir Sydney Sunderland and more recent work by other authors has been included. Our studies confirm that there is a complex interfascicular relationship between the various components of the median and ulnar nerves in the forearm and hand, but, with careful dissection, several anatomic relationships can be defined. Individual branches and bundles can be traced within the main nerve trunks for considerable distances without significant trauma to the conducting fibers. These include the recurrent branch of the median nerve, the branches to the lumbrical muscles, the motor and sensory components of the ulnar nerve, and the dorsal sensory branch of the ulnar nerve. These findings have a direct relationship to the clinical repair of fresh nerve injuries as well as those injuries that require nerve grafting for significant gaps in the neural tissue. Intraneural neurolysis can be safely performed if detailed knowledge of the internal topography of the peripheral nerves is understood. This knowledge may also be applied to the dissection and management of neuromas in continuity. The increased awareness of the interfascicular relationships of the peripheral nerves may well influence a more favorable outlook in the care of patients with nerve injuries.