Functional units within the latissimus dorsi muscle based on Sihler technique

The latissimus dorsi is the largest dorsally located pectoral girdle muscle. The anatomic basis for splitting this muscle is based on dissection studies. These dissection studies have outlined the extramuscular innervation of the muscle. The intramuscular innervation, on the other hand, has been studied by using radiographs of intramuscular nerves labeled by fine wire. This technique, however, is limited by the level of microdissection that can be performed. Sihler staining technique renders the muscle translucent, stains the myelin in the nerve a dark blue and the hemoglobin in the vessels a dark brown. The intramuscular course and branching of the nerve and vessels is thus revealed without any surgical disruption of the anatomy. We use this technique to study the intramuscular neurovascular anatomy of the latissimus dorsi flap in 6 fresh human cadavers to determine the degree to which the muscle could be separated for functional muscle transfer.