Variations in the vascular pedicle of the rat gracilis muscle flap.

The rat gracilis muscle is a reliable model for microsurgical research. Exploration of 364 inguinal regions and preparation of 80 free gracilis muscle flaps in Sprague-Dawley and Lewis rats revealed six distinct origins of the dominant arterial pedicle and four variations of the venous pedicle. Popliteal, external iliac, and truncus pudendoepigastricus associations are described for the first time in this study. The total incidence of atypical variation of arterial pedicle origin is 20.7 percent. The most common origin of muscular branch arteries are the superficial epigastric artery (53.3 percent), femoral artery (22.0 percent), popliteal artery (14.6 percent), and the external iliac arteries (5.5 percent). Muscular branch veins drain most frequently into the femoral vein (79.1 percent). Gracilis muscle flaps prepared from rats weighing 329 +/- 45 g weighed an average of 0.64 +/- 0.13 g, and their volume averaged 0.87 +/- 0.12 ml. Muscular branch artery and vein diameters (external) averaged 0.21 +/- 0.05 mm and 0.54 +/- 0.06 mm, respectively. This new anatomic information is essential for reproducible microsurgery research using the rat gracilis muscle.