Objective: For purposes of neurotization of the musculocutaneous nerve (MCN) with the medial pectoral nerve (MPN) after upper trunk brachial plexus injuries, the anatomic relationship between these two nerves was defined in a cadaveric model.
Methods: Thirty-five brachial plexuses in 18 adult cadavers were dissected. The distance between the origin of the MPN from the medial cord to the origin of the MCN from the lateral cord was measured. The length, diameter, branching, and location of the MPN were recorded. The diameter of the proximal MCN was recorded.
Results: Thirty-seven percent of the MPNs, when detached from the pectoralis muscles, were too short to reach the proximal MCN by a mean distance of 15 mm. The MPN pierced the pectoralis minor muscle in 80% of the dissections. The cross sectional area of the MCN was always larger than the cross sectional area of the MPN by an average factor of 2.5.
Conclusion: When planning to use the MPN for neurotization of the MCN, one should be prepared to harvest an interposition graft, because over one-third of MPNs may not have enough length to reach the MCN in a tension-free manner. Diameter mismatch occurs predictably between the distal MPN and the proximal MCN.