Superior ulnar collateral artery

The superior ulnar collateral artery is a branch of the brachial artery that arises in the mid-arm and serves as the dominant longitudinal arterial source to the ulnar nerve in the upper arm, as well as a key contributor to the medial vascular arcade of the elbow.

Origin and Course

The superior ulnar collateral artery originates from the medial aspect of the brachial artery in the mid-arm. It descends along the medial side of the arm in close relation to the ulnar nerve, accompanying the nerve as it courses posteriorly toward the elbow. The artery has a mean external diameter of approximately 2.0 mm and a mean length to its first neural branch of approximately 76 mm. It gives off fasciocutaneous branches that supply the medial aspect of the arm — in approximately 68% of cases, a superficial fasciocutaneous branch arises from the superior ulnar collateral artery and travels dorsal to the ulnar nerve in about 64% of specimens. Additional fasciocutaneous pedicles (3–4) originate from the superior ulnar collateral artery to supply the middle and lower portions of the medial arm.

Anastomoses and Vascular Arcade

At the elbow, the superior ulnar collateral artery participates in the medial vascular arcade, which is formed by the superior ulnar collateral artery, the inferior ulnar collateral artery, and the posterior ulnar recurrent artery. This arcade is part of the broader anastomotic network around the elbow (rete articulare cubiti). Notably, no identifiable direct anastomosis between the superior ulnar collateral artery and the posterior ulnar recurrent artery was found in 20 of 22 cadaveric specimens in one study, with the inferior ulnar collateral artery serving as the bridging vessel between these two territories. The superior ulnar collateral artery also contributes to collateral circulation when the brachial artery is occluded distal to its origin, anastomosing with the inferior ulnar collateral, radial recurrent, ulnar recurrent, and dorsal interosseous arteries to maintain distal perfusion.

Territories of Supply

• Ulnar nerve in the arm: The superior ulnar collateral artery is the main contributing vessel to the ulnar nerve in the arm, providing segmental nutrient branches. The average length of these nutrient vessels is approximately 2.6 cm.

• Medial arm skin and fascia: Through its fasciocutaneous branches, the superior ulnar collateral artery vascularizes the medial aspect of the arm, forming the basis for medial brachial flaps (both proximally and distally pedicled).

• Elbow region: As part of the medial arcade, it contributes to the periarticular and intraosseous blood supply of the medial elbow.

Clinical Significance

The superior ulnar collateral artery is surgically relevant in several contexts:

• During anterior transposition of the ulnar nerve for cubital tunnel syndrome, the extrinsic vascular supply from the superior ulnar collateral artery can be preserved even after extensive nerve mobilization.

• The superior ulnar collateral artery serves as a reliable vascular pedicle for vascularized ulnar nerve grafts, particularly in contralateral C7 transfer procedures for brachial plexus reconstruction, given its consistent anatomy and adequate caliber.

• It provides the vascular basis for raising distally-pedicled medial brachial flaps for coverage of soft tissue defects around the elbow.