Anatomical Research of the Three-dimensional Route of the Thoracodorsal Nerve, Artery, and Veins in Latissimus Dorsi Muscle

Background: The latissimus dorsi (LD) muscle flap has been widely used in facial reanimation surgery. However, there are no standards to what degree the muscle flap may be safely thinned because the three-dimensional positional relationship of thoracodorsal artery, vein, and nerve inside the LD muscle is poorly understood. Methods: From 18 formalin-fixed cadavers, we made 36 transparent specimens of LD muscles using a newly developed decoloration technique. In 26 specimens, nerve staining (Sihler’s staining method) and silicone rubber (Microfil) injection to the thoracodorsal artery were performed, and the relationship of the artery and the vein was examined in 10 specimens. Results: The thoracodorsal artery and vein always ran parallel in a deeper layer compared to the nerve. The thoracodorsal nerve constantly existed in a deeper layer than half (50%) of the muscle in the range of use of the muscle flap in facial reanimation surgery. Conclusions: The thoracodorsal nerves ran in a shallower layer, and the depth to the nerve in the muscle flap in actual facial reanimation surgery is safe enough to avoid damage to the nerves. The LD muscle may be thinned to half its original thickness safely.