Vascular anatomy of the ulna

The vascular anatomy of the ulna was studied. Ten fresh-frozen upper extremity specimens were injected with India ink and latex solution. The extraosseous anatomy was dissected. The intraosseous anatomy was evaluated after treatment with the modified Spalteholtz technique. The proximal periarticular portion of the ulna was supplied by numerous, very small periarticular branches running in the capsule. A major intramedullary nutrient vessel arose from the ulnar artery or ulnar recurrent artery in all specimens and entered at the base of the coronoid. The ulnar artery gave off a common interosseous artery that branches into posterior and anterior interosseous vessels that course distally on the interosseous membrane. The interosseous vessels were critical for they supply the only observed vascular branches to the ulna diaphysis. The anterior interosseous vessel supplied on average 7 branches (range, 3-11 branches) to the ulna diaphysis spaced at generally regular 2-cm intervals, with the number of branches decreasing in the distal third. The posterior interosseous artery supplied an average of 11 branches (range, 9-14 branches) to the ulna diaphysis spaced at 1-cm intervals. The distal ulna metaphysis was supplied by terminal branches of the anterior interosseous artery. The ulnar head was supplied by small branches off the ulnar artery proper. In summary, the blood supply to the ulna diaphysis was dependent on segmental vessels provided by the anterior and posterior interosseous vessels. No dominant intramedullary vessel was observed in the diaphysis. The interosseous vessels should be protected when treating a ulna fracture or a nonunion, or when performing an osteotomy.