The relationship between the morphology and dominance of the arteries in the palm.

The main arteries supplying the forearm and hand are the radial and ulnar arteries. Multiple anastomoses exist between these arteries, and insights into the course of these arteries within the collateral circulation and their dominance hold clinical significance as a basis for surgical applications involving the radial artery. In particular, the morphology of the superficial palmar arch shows a significantly high variance. Embryologically, an archetypal superficial palmar arch arises as the radial artery-which extends from the brachial artery-anastomoses with the ulnar artery in the palm, from which the median artery eventually regresses. However, the resultant dominance of the arteries in the superficial palm remains unclear, and its relationship with arterial topology has not been fully investigated. In this study, the courses of the superficial palmar arch and the outer diameters of the radial and ulnar arteries were examined and recorded in 57 sides of 31 cadavers. The results confirmed that the ulnar artery was mostly dominant in the superficial palmar branches. Interestingly, two cases were observed in which the radial artery was dominant in the superficial palmar branches; in both cases, the superficial palmar arch was formed by the radial-ulnar artery, suggesting a common developmental mechanism. Based on our observations, we propose that the morphology of the superficial palmar arch is influenced by the blood supply from the ulnar artery to the palm during the early stages of development.