The hand contains an extensive network of arteries designed to ensure a constant and robust blood supply. This intricate vascular system is necessary because the hand is one of the most functionally complex parts of the human body. Its continuous use and high degree of mobility require significant oxygen and nutrient delivery to sustain complex muscle and nerve function. The hands are also frequently exposed to potential injury, making a resilient blood supply mechanism a biological necessity.
The Major Supply Lines to the Hand
The blood flow to the hand originates from two large vessels that travel down the forearm: the radial artery and the ulnar artery. These two arteries separate at the elbow, continuing the circulation from the single brachial artery of the upper arm. The radial artery follows a path along the thumb side of the forearm and can be easily felt near the wrist. This artery supplies the posterolateral aspect of the forearm and is frequently used for medical assessments.
The ulnar artery runs along the pinky finger side of the forearm, supplying the anteromedial compartment. Near the wrist, the ulnar artery enters the palm, traveling laterally to the ulnar nerve. Both vessels contribute to intricate networks that ensure the hand receives blood from two distinct sources, providing a circulatory safety margin. Their paths terminate near the wrist, where they diverge to form the specialized loops within the hand structure itself.
The Artery Network within the Palm
Upon reaching the hand, the radial and ulnar arteries converge and connect to form two major, arch-like structures known as the palmar arches. This connection, called an anastomosis, is a crucial feature that creates a continuous loop of circulation. The Superficial Palmar Arch is located closer to the surface of the palm and is formed predominantly by the ulnar artery. It lies across the center of the palm, deep to the palmar aponeurosis and superficial to the long tendons that flex the fingers.
Lying deeper within the hand is the Deep Palmar Arch, which is mainly formed by the continuation of the radial artery. This deeper arch sits on the bases of the metacarpal bones and provides blood supply to the deep muscles and joints of the hand. The arches are connected to each other, and this dual-source, interconnected structure creates an extensive collateral circulation.
This collateral circulation allows the hand to maintain blood flow even if one of the main arteries is blocked or injured. Branching off these two arches are the palmar digital arteries, which extend toward the fingers. These digital arteries travel alongside the fingers, providing the necessary blood supply to the muscles, skin, and bone structure of the digits. The arrangement ensures that every part of the hand is constantly perfused with oxygenated blood.
Practical Implications of Hand Circulation
The radial artery’s position near the wrist bone makes it a common location for checking a pulse, as the vessel is superficial and easily compressed. This point, immediately lateral to the tendon of the flexor carpi radialis muscle, offers a clear measure of heart rhythm and blood flow.
The high density of blood vessels means that even a small cut can result in significant bleeding. However, the interconnected nature of the palmar arches often prevents catastrophic outcomes in the event of injury to a single vessel. Because the hand receives blood from both the radial and ulnar arteries, the entire structure can often remain nourished even if one source is compromised. The collateral circulation is sometimes assessed using clinical tests before procedures involving the radial artery to confirm that the ulnar artery can adequately sustain the hand’s blood supply alone.