Two Circumflex Humeral Arteries in the Arm, with Special Reference to their Communications

The anterior and posterior circumflex humeral arteries were examined in 31 upper extremities of 18 Japanese adults, with the main emphasis being laid on the anastomoses between them. After arising from the axillary artery, the anterior circumflex artery passed laterally deep to the biceps brachii, and on the lateral side of the long head of the biceps, it was divided into the following four arteries,1) ascending branch to the shoulder joint,2) descending branch to the insertion of the pectroralis major,3) transverse branch to the periosteum of the humerus and 4) muscular branch to the deltoideus. The last two were concerned with the anastomoses between the two circumflex arteries. The authors could observe the anastomoses in less than half of the examined cases macroscopically, but most of them formed part of the arterial network on the periosteum of the humerus or were found within the deltoid muscle. If defined in a strict sense and taking only the cases into consideration in which they were found outside the muscle as moderately thick branches, anastomoses were observed in only 4cases (13%). The anterior circumflex artery was mainly distributed to the periosteum, joint capsule and muscle tendon, whereas the posterior circumflex artery was distributed to the deltoid muscle. The origin of the former was fairly constant, arising from the stem of the axillary artery deep to the median nerve, but the latter had a variable origin. No compensating relations were observed between the two. In conclusion, it was found that these two arteries did not have such an intimate relationship with each other as most textbooks of anatomy have described.