High origin of a superficial ulnar artery arising from the axillary artery: anatomy, embryology, clinical significance and a review of the literature.

The superficial ulnar artery (SUA) is an ulnar artery of high origin that lies superficially in the forearm. Its reported frequency ranges from 0.17% to 2%. During anatomical dissection in our department we observed a unilateral case of SUA in a 75-year-old white male human cadaver. It originated from the right axillary artery at the level of the junction of the two median nerve roots and followed a looping course, crossing over the lateral root of the median nerve and running lateral to it in the upper and middle thirds of the arm, whereas in the inferior third of the arm the SUA crossed over the median nerve and ran medially to it. In the cubital fossa, it passed superficially over the medial side of the ulnar aponeurosis and coursed subcutaneously in the ulnar side of the forearm superficially to the forearm flexor muscles. In the hand the SUA anastomosed with the superficial palmar branch of the radial artery, creating the superficial palmar arch. Additionally, it participated in the development of the deep palmar arch. The axillary artery, after the origin of the SUA, continued as the brachial artery and divided into the radial and common interosseous arteries in the cubital fossa. The normal ulnar artery was absent. No muscular or other arterial variations were observed in this cadaver. The embryological interpretation of this variation is difficult and it may arise as a result of modifications to the normal pattern of capillary vessel maintenance and regression. The existence of a SUA is undoubtedly of interest to the clinician as well as to the anatomist. This report presents a case of unilateral SUA along with a review of the literature, embryological explanation and analysis of its clinical significance.