Comparative anatomy and histochemistry of human and canine latissimus dorsi muscle.

Gross and histologic studies of human and canine latissimus dorsi muscle were carried out to identify anatomic and histochemical properties that may be relevant to its use as a resource muscle, particularly for heart reconstruction. In both human and canine latissimus dorsi, three distinct muscle segments were observed, differing in direction of fibers, fiber characteristics, thickness, and blood supply. The entire canine latissimus dorsi could also be separated into superficial and deep layers, whereas only the anterolateral segment of human latissimus dorsi was separated further by the neurovascular bundle. Histochemical studies suggested significant differences between the ratios of fast to slow fibers in the superior and anterolateral segments of human muscle. Variation in size, weight, and shape within and between subjects demonstrates a need for careful evaluation of the potential resource muscle.