Objective To compare the anatomical differences between the anconeus and the abductor pollicis brevis (APB), in order to provide anatomical features of the anconeus for its suitability as the free muscle flap for restoration of thumb oppositional function. Methods Nine Chinese cadavers with elbow, forethigh and plam of hand preserved well were collected. By using standard calipers and Image J 1.45 d, we gave a quantitative description of muscle architecture and the neurovasculature involved in the operative planning of restoration thumb oppositional function in which anconeus free muscle flap is used. Results The mean measures of the anconeus were larger than those of the APB ［anconeus/APB fiber length=(82.0±12.0)mm/(51.6±8.3)mm, area=(936.7±221.8)mm²/(704.4±244.2)mm²］. There was no significant difference between mean fiber angles (anconeus/ APB=60.9°±10.2°/71.2°±11.7°; P>0.05) and neurovasculature ［anconeus/APB:artery diameter=(1.9±0.2)/(2.0±0.5)mm, nerve diameter=(1.7±0.3)/(2.1±0.4)mm; P>0.05］. The length (32.0±3.1)mm and caliber ［diameter=(1.16±0.28)mm］of the vascular pedicle of the anconeus(recurrent posterior interosseous artery) and its venae comitans (diameter=0.8 mm) were sufficient for microsurgical anastomosis. Conclusion The anatomic rationale of the anconeus free muscle flap for thenar reconstruction is suitable and compared to other free muscle flap. It has some advantages: reliable and matching anatomy, minimal donor site morbidity, and the potential to restore a greater degree of opposition and thus function in a one-stage procedure.