Radial Artery
The radial artery (a. radialis) branches off from the brachial artery in the cubital fossa and courses inferiorly and laterally. Initially, it lies on the anterior surface of the pronator teres muscle, then descends between the brachioradialis and flexor carpi radialis muscles. In the distal third of the forearm, the vessel is covered only by fascia and skin, where it is easily compressed against the radius to check the pulse.
Next, the artery curves posteriorly, crossing the bones of the anatomical snuffbox (over the scaphoid bone), passes beneath the tendon of the extensor pollicis longus muscle, and enters the palm through the first interosseous space. In the hand, it serves as the primary contributor to the deep palmar arch.
Key Branches:
- Radial recurrent artery (a. recurrens radialis) — ascends to the lateral epicondyle, contributing to the elbow vascular network.
- Superficial palmar branch (r. palmaris superficialis) — crosses the thenar eminence and joins the superficial arch.
- Carpal branches (palmar and dorsal) — participate in the carpal networks.
- Principal artery of the thumb (a. princeps pollicis) — divides into two collateral branches for the thumb (digit I).
- Radiais indicis artery (a. radialis indicis).
Ulnar Artery
The ulnar artery (a. ulnaris) is typically the larger terminal branch of the brachial artery. From the cubital fossa, it runs medially and anteriorly, passing deep to the pronator teres. In the forearm, it travels between the superficial and deep flexor digitorum muscles, and in its middle and distal thirds, it occupies the groove between the flexor carpi ulnaris and flexor digitorum superficialis muscles. In its distal segment, the ulnar nerve joins it on its medial side.
It enters the palm anterior to the pisiform bone, superficial to the palmar aponeurosis, and continues as the main continuation of the superficial palmar arch.
Key Branches:
- Ulnar recurrent artery (a. recurrens ulnaris) — gives off anterior and robust posterior branches to the medial epicondyle.
- Common interosseous artery (a. interossea communis) — a short trunk that splits into the anterior interosseous artery (running on the interosseous membrane) and posterior interosseous artery (passing to the posterior forearm).
- Deep palmar branch (r. palmaris profundus) — crosses the palm beneath the flexor tendons to complete the deep arch.
Palmar Arches and Vascular Networks
Two major arterio-arterial anastomoses form in the hand to protect the digits from ischemia during gripping:
- Superficial palmar arch (arcus palmaris superficialis). Formed primarily by the ulnar artery with a contribution from the superficial palmar branch of the radial artery. It lies deep to the palmar aponeurosis. It gives rise to three common palmar digital arteries, which bifurcate into proper digital arteries for the adjacent sides of digits II–V.
- Deep palmar arch (arcus palmaris profundus). Primarily supplied by the radial artery, completed by the deep palmar branch of the ulnar artery. Located more deeply, across the bases of the metacarpal bones. It gives rise to palmar metacarpal arteries (reinforcing the superficial arch) and perforating branches to the dorsum of the hand.
Additionally, the following networks are distinguished in the forearm and hand:
- Elbow articular network (rete articulare cubiti) — anastomoses collateral branches of the arm with recurrent branches of the radial, ulnar, and interosseous arteries.
- Dorsal carpal network (rete carpi dorsale) — formed by the dorsal carpal branches of both main arteries and the posterior interosseous artery. It gives rise to dorsal metacarpal arteries.