Radial collateral artery

The radial collateral artery is a terminal branch of the deep brachial artery (profunda brachii) that courses along the lateral aspect of the arm, accompanying the radial nerve through the radial (spiral) groove of the humerus toward the elbow region.

Origin and Course

The radial collateral artery arises as a continuation of the deep brachial artery after the latter gives off the middle collateral artery. The deep brachial artery, which is the first and largest branch of the brachial artery (with a mean diameter of approximately 2.05 mm), consistently bifurcates after the origin of the middle collateral artery into the radial collateral artery proper. In cadaveric studies, the radial collateral artery has been measured at approximately 3.5 mm in diameter at the level of the dorsal humerus.

Terminal Branches

The radial collateral artery divides into two terminal branches:

• Anterior radial collateral artery (ARCA): Descends anterior to the lateral epicondyle and anastomoses with the radial recurrent artery, contributing to the periarticular vascular network of the elbow.

• Posterior radial collateral artery (PRCA): Descends posterior to the lateral epicondyle, supplying the posterolateral skin of the arm and giving off musculocutaneous perforators. This branch is the vascular basis for the lateral arm flap used in reconstructive surgery.

Contribution to the Elbow Vascular Arcades

The radial collateral artery is a key component of the lateral vascular arcade of the elbow, which is formed by the radial collateral, middle collateral, radial recurrent, and interosseous recurrent arteries. This arcade provides the blood supply to the capitellum and the lateral aspect of the trochlea through posterior perforating vessels. The middle collateral artery anastomoses transversely with the inferior ulnar collateral artery, contributing to the anastomotic circle of the elbow.

Anatomical Variations

While the most common origin is from the deep brachial artery, the radial collateral artery may occasionally arise directly from the brachial artery. Variations in its origin have been identified in approximately 13–20% of specimens in cadaveric and Doppler sonographic studies.

Clinical Significance

• The radial collateral artery accompanies the radial nerve along the dorsal humerus, making it a critical landmark during posterior approaches to humeral shaft fractures; iatrogenic injury to either structure is a recognized surgical risk.

• The posterior radial collateral artery serves as the primary pedicle for the lateral arm flap and the "extreme" lateral arm flap, used for reconstruction of soft tissue defects of the forearm and hand.

• The radial collateral artery contributes to the collateral circulation that maintains perfusion to the forearm and hand in cases of brachial artery occlusion.