The radial artery is a major blood vessel in the forearm that carries oxygenated blood from the heart down to the hand. It is one of the two main arteries of the forearm, branching off from the larger brachial artery near the elbow. Its location close to the skin’s surface at the wrist makes it easily accessible for routine checks and various medical procedures, providing important information about circulatory status.
Anatomical Location and Course
The radial artery begins in the upper forearm, originating from the bifurcation of the brachial artery in the antecubital fossa, just below the bend of the elbow. It is the smaller of the two terminal branches, the other being the ulnar artery. The artery then travels down the forearm along the radius bone, which is on the thumb side of the arm, hence its name.
In the upper forearm, the artery is deeper, partially covered by the brachioradialis muscle. As it moves toward the wrist, it becomes more superficial, lying just beneath the skin and fascia. It runs between the tendons of the brachioradialis and the flexor carpi radialis muscles, resting directly on the lower end of the radius bone.
The artery then winds laterally around the wrist, passing through the anatomical snuffbox on the back of the hand. It eventually re-enters the palm, where it contributes to the formation of the deep palmar arch. This arch is a network of blood vessels that connects with a branch of the ulnar artery, ensuring continuous blood supply to the hand.
Locating and Assessing the Radial Pulse
Finding the radial pulse involves locating the artery where it runs most superficially against the radius bone, on the thumb side of the wrist. Turn your hand so the palm is facing up, and look for the area between the wrist bone and the prominent tendon on the thumb side.
Use the pads of your index and middle fingers to gently press into the hollow space located on the thumb-side of the wrist. It is important to avoid using your thumb to feel the pulse, as your thumb has a strong pulse of its own that could be confused with the patient’s. Apply just enough pressure to feel the distinct, rhythmic throbbing of the artery as blood is pushed through it.
Once the pulse is located, the assessment measures three main characteristics: rate, rhythm, and strength. The rate is the number of beats per minute, which can be counted for a full 60 seconds, or for a shorter interval like 30 seconds and then multiplied by two. The rhythm should be checked for regularity, and the strength, or volume, is assessed to see if the pulse feels strong and full or weak and thready.
Clinical Use and Testing
Beyond routine heart rate checks, the radial artery’s accessibility makes it a common access point for specialized clinical procedures. One frequent medical use is for drawing arterial blood gas (ABG) samples, which measure the oxygen, carbon dioxide, and acidity levels in the blood. This arterial blood provides a precise snapshot of a patient’s respiratory and metabolic status.
Because accessing the radial artery carries a slight risk of causing a clot that could disrupt blood flow, a precautionary measure called the Allen test is performed beforehand. This test assesses the collateral circulation in the hand, specifically checking if the ulnar artery can provide sufficient blood flow as a backup. If the radial artery were to become compromised, the ulnar artery and the connecting palmar arch must be patent to prevent tissue damage.
The Allen test involves the patient clenching their fist while a healthcare professional compresses both the radial and ulnar arteries, causing the hand to blanch. Pressure is then released from the ulnar artery, and the time it takes for the hand’s normal color to return is measured. A rapid return to color, typically within 5 to 7 seconds, indicates adequate collateral circulation, confirming the radial artery can be safely used for the procedure.
The radial artery is also commonly used for inserting arterial lines for continuous blood pressure monitoring, and sometimes for harvesting the vessel for use in coronary artery bypass graft surgery.