Background: In previous literature, the anterior (Ac) and posterior (Pc) circumflex humeral arteries were supposed to communicate with each other around the surgical neck of the humerus. However, actual anastomoses between these arteries were rarely observed. The purpose of the present study is examine the origins, courses, and distributions of Ac and Pc.
Materials and Methods: We evaluated 44 shoulders from 25 cadavers including 21 right and 23 left shoulders.
Results: In all specimens, Ac directly originated from the axillary artery, sent branches into the insertion of the subscapularis, and then, ascended along the long head of biceps. In some specimens, Ac passed under the long head of biceps. Pc originated from the axillary artery or the subscapular artery, and went around behind the humerus. Pc ran anteriorly from the middle to anterior portion of the deltoid sending branches into them. The diameter of the origin of Ac was an average of 1.7mm (SD; 0.4) and that of Pc was 3.5mm (SD; 0.9). The diameter of Ac was significantly smaller than that of Pc.
Conclusion: There were no direct anastomoses between Ac and Pc through thick arteries, while they made anastomoses through a capillary vessel inside or outside the deltoid muscle. The running course of each artery was separated by the conjoined tendon, long head of biceps, pectoralis major and subdeltoid bursa. Based on the present results, Ac and Pc would not make a complementary relation, and each artery might have an independent function.
