The dominant blood supply to the latissimus is the thoracodorsal artery. The thoracodorsal is a continuation of the subscapular branch of the axillary artery, after the subscapular gives off the circumflex scapular. The thoracodorsal gives off a branch to the serratus before reaching the deep surface of the latissimus 8-10 cm from its humeral insertion. The muscular branches fan out, making it possible to split the muscle along the lines of its fibers into more than one flap. Perforating vessels can support a large overlying skin island.
The margins of the skin island were incised down to deep fascia, beveling away from the island to capture the maximum number of perforating vessels for viability. Flaps were developed above and below the island to the borders of the latissimus.
Link to this frame from your Personal Thumbnails page?