Unusual variation of the arterial pattern of the human upper limb.

The anomalous brachial artery, after giving off a profunda brachii artery with no collaterals, divides in its upper one-third into two equal-sized arteries, brachial arteries #1 and 2. These arteries lie next to each other in the normal path of the brachial artery. Brachial artery #1 is possibly a high-origin and persisting radial artery. It gives no collaterals in the arm. At the cubital fossa, it becomes subcutaneous and divides into two equal-sized radial and ulnar arteries. These arteries run completely superficial to flexor muscles of the forearm and are terminated by branches running above the thenar and hypothenar eminences, respectively. Brachial artery #2 is possibly a high-origin artery of the common interosseous. The course of this artery resembles the course of the brachial axial artery of the embryo. It supplies the anterior compartment of brachial muscles and continues as the common interosseous artery. This common interosseous artery in turn branches into the superior and inferior ulnar collaterals, and the anterior and posterior interossei. It does not regress, but has a major role in forming the deep palmar arterial arch in the hand. The clinical implications of such an anomaly are discussed.