One of the two main arteries of the forearm, the radial artery runs from the cubital fossa at the elbow to the carpal region of the hand to form the palmar arch, where it links up with the ulnar artery. It delivers blood to the elbow joint, lateral forearm muscles, radial nerve, the carpal bones and joints, thumb as well as the lateral side of the index finger.
The terminal branch of the brachial artery of the upper arm, the radial artery runs beneath the brachioradialis (a major muscle of the forearm) from the cubital fossa just past the elbow through the carpal region of the wrist, before ending at the palmar arch of the hand. Smaller than the ulnar artery—the other major source of blood for the arm and hand—it proceeds on the radial side of the arm, which is the one closer to the thumb (as opposed to the pinkie).
At that point, it winds back around the carpus, the set of bones in the wrist, beneath the tendons of the hand’s abductor pollicis and pollicis longus muscles that regulate thumb movement. Crossing through the flat portion of the hand between the thumb and index finger (known as the “anatomic snuffbox”), before reaching the inner palm of the hand. After passing through the metacarpal bones there, the radial artery terminates in the palm, as it joins with the ulnar artery.
This important artery is divided into three sections: one in the forearm, the second in the wrist, and the third in the palm of the hand. There are several major branches from the artery in these areas:
- In the forearm: The radial recurrent artery starts just below the elbow, ascending through branches of the radial nerve on top of the supinator (the broad muscle at the top of the forearm) and later between the two muscle groups lower down—the brachioradialis and brachialis. The volar carpal network, down toward the wrist, splits off to supply the wrist with blood. In addition, the superficial volar branch splits off right at the point where the radial artery starts winding around the lateral side of the wrist.
- At the wrist: The dorsal carpal branch is a small vessel that emerges from the radial artery beneath the extensor tendons of the thumb and joins a section of the ulnar artery to form the dorsal carpal network. From there, the dorsal metacarpal arteries arise and travel down to supply the middle and smaller fingers with blood. In addition, the first dorsal metacarpal artery, which supplies the index finger and thumb, arises here.
- In the hand: Branching from the radial artery in the hand as it turns towards the deep palm, the arteria princeps pollicis provides additional blood to the thumb muscles. The arteria volaris indicis radialis arises nearby and descends down the index finger. The radial artery terminates in the deep volar arch, which is where it meets up with the ulnar artery. It’s located at the extremities of the metacarpal bones (the segment of the fingers closest to the wrist).
The most common variation in structure—seen in approximately 5.1% of people—is that the radial artery breaks off from the brachial artery higher than usual.
In rarer cases are deviations seen in the forearm; however, the artery has been observed closer to the exterior on top of the deep fascia layer. It can also run on top of, rather than beneath, the brachioradialis muscle of the forearm.
Doctors have also observed the artery on the surface of the thumb’s extensor tendons, rather than beneath them.
Primarily, the radial artery supplies blood to the elbow, the lateral forearm muscles, the radial nerve, the carpal tunnel bones and joints, thumb, and lateral side of the index finger.
Because of its position closer to the surface of the skin, the radial artery can be used to measure the pulse at the wrist.
In addition, blood drawn from this artery is used for arterial blood gas (ABG) tests, which determine levels of oxygen, carbon dioxide, and other gasses in the blood. This test is often performed as part of intensive care procedures.
Though the radial artery isn’t the only supplier of blood to the hand and forearm, disorders or diseases there can severely impact function. Several conditions can arise due to circulation problems there.
- Carpal tunnel syndrome: While not the most common reason for carpal tunnel syndrome—characterized by pain, numbing, and tingling in the arm and hand—about three percent of cases have been linked to aberrations of the radial artery.
- Raynaud’s syndrome: Problems with radial artery can also lead to Raynaud’s syndrome, a condition in which small arteries and veins in the hands constrict in response to colder temperatures. This causes the skin to turn pale or blue, and fingertips to go numb.
- Upper extremity arterial occlusive disease: Often the result of atherosclerosis, when arteries become thick and stiff, upper extremity arterial occlusive disease is a disruption of proper blood flow in the upper limbs . Though these types of problems are more common in the lower body, this issue can sometimes lead to discomfort or pain, tightness, cramping, or weakness in the arm.