Segmentally split pectoral girdle muscle flaps for chest-wall and intrathoracic reconstruction.

The latissimus dorsi, pectoralis major, and serratus anterior provide the principal flaps for major chest-wall and intrathoracic reconstructions. Each of these muscles shows a philogenetically preserved internal metamerism that is expressed by a segmental morphology and neurovascular supply. This segmental anatomy creates multiple independent subunits in each muscle that can be surgically split and independently used. Surgically splitting these muscles permits flap refinements such as creating two flaps from one donor muscle and leaving independent subunits in situ to preserve donor motor function after flap transfer. The latissimus dorsi has a consistent proximal bifurcation of its neurovascular supply into a medial and lateral branch that permits dividing the muscle or skin-muscle unit into two independent flaps. The pectoralis major has three segmental neurovascular subunits, the clavicular, the sternocostal, and the external. These can be surgically split and independently transferred on vascular pedicles from the thoracoacromial, internal mammary, and lateral thoracic vessels. This provides a substantial degree of donor motor preservation, as shown by the pectoralis V-Y myoplasty for mediastinal reconstruction. The serratus arterial has a highly segmental morphology with multiple subunits corresponding to each of the first nine costovertebral units; it also can be surgically split. The resultant upper and lower groups can be further subdivided if needed. These flaps provide useful intrathoracic reconstruction with a substantial degree of donor motor preservation. Such technical refinements substantially increase each flap's versatility and lessens the donor cost for thoracic reconstruction.