The radial artery is a continuation of the brachial artery and is one of the major blood supplying vessels to the structures of the forearm. The brachial artery terminates at the cubital fossa where it bifurcates into the ulnar artery and a smaller radial artery. It runs on the lateral aspect of the forearm before it reaches the wrist and branches out to supply the hand. The radial artery is also important clinically due to its location at the wrist, as it can be felt as a pulse and can be used to determine the heart rate.
The radial artery begins at the inferior portion of the cubital fossa after it has bifurcated from the brachial artery (a continuation of the axillary artery), but it appears almost as a direct continuation of the brachial artery.
In the forearm, the radial artery travels down from the medial aspect of the neck of the radius to the styloid process of the anterior surface of the radius. Proximally, the artery lies deep to the brachioradialis muscle while distally it is only covered by fascia and skin. It lies between the tendon of the brachioradialis and the flexor carpi radialis muscles. Lying deep to the radial artery is the common tendon of the biceps brachii, pronator teres, supinator and flexor digitorum superficialis muscles.
Wrist & Hand
At the wrist, the radial artery goes around it laterally and then travels across the floor of the anatomical snuffbox to the palm of the hand.
The radial artery has many branches occurring at the forearm, wrist and hand. Below are the major branches of the radial artery:
These small branches supply muscles on the radial aspect of the forearm, in particular the extensor muscles of the posterior compartment of the forearm.
Radial Recurrent Artery
This branch is just distal to where the radial artery has bifurcated from the brachial artery. It anastamoses with the radial collateral artery (derived from the deep brachial artery) and is an important blood supply to the elbow joint.
Palmar Carpal Branch
This branch arises near the distal border of the pronator quadratus muscle and runs along the anterior surface of the carpal bones. It anastamoses with the palmar carpal branch of the ulnar artery and the anterior interosseous arteries. This forms the palmar carpal arch to supply the carpal bones and their joints.
Dorsal Carpal Branch
The dorsal carpal branch branches off from the radial artery at the proximal part of the anatomical snuffbox and runs medially across the wrist. It anastamoses with the dorsal carpal branch of the ulnar artery and posterior interosseous arteries to form the dorsal carpal arch.
Superficial Palmar Branch
This branch completes the lateral part of the superficial palmar arch, which is predominately supplied by the direct continuation of the ulnar artery. The superficial palmar arch lies between the long flexor tendons of the digits and the palmar aponeurosis.
Deep Palmar Branch
This branch is a direct continuation of the radial artery and forms the deep palmar arch of the hand. The medial aspect of the deep palmar arch is completed by the deep palmar branch of the ulnar artery. The deep palmar arch runs through the palm between the bases of the metacarpal bones and the long flexor tendons of the digits.
First Dorsal Metacarpal Artery
This branch artery splits into two and supplies the adjacent sides of the thumb and index finger.
Princeps Pollicis Artery & Radialis Indicis Artery
When the radial artery reaches the level of the webspace between the thumb and index finger it splits into two branches on the dorsal aspect of the hand: the princeps pollicis artery and radialis indicis artery. The princeps pollicis branch divides into two and is the main blood supply to the thumb of the hand. The radialis indicis branch runs along to the distal end of the index, supplying the lateral aspect of the index finger.
Radial Arterial Pulse
As alluded to above, the radial artery at its distal end of the forearm (i.e. before the wrist) lies on the anterior surface and is only covered by skin and fascia. This is a common place to measure the pulse rate of a patient as a means to assess heart rate, cardiac rhythm and pulse strength.
The radial pulse on each forearm can be simultaneously measured to assess any radioradial delays in the presence of an aortic dissection, or compared to the femoral pulse to assess any radiofemoral delays to detect a possible aortic coarctation.
The branches of the radial artery and ulnar artery anastamose with each another in the hand to form the superficial and deep palmar arches (and dorsal carpal arch). The Allen’s test assesses whether there is adequate or abnormal circulation in the hand via these arches.
At the wrist, the radial and ulnar artery are compressed. The ulnar artery is then released and the pattern of filling in the hand is observed and assessed. The Allen’s test plays an important role as a screening method to assess circulation of the hand before harvesting the radial artery to be used as an arterial conduit for a coronary artery bypass graft. The radial artery is an ideal graft candidate due to its diameter, length and ease of harvesting of the blood vessel. This test can also be used before sampling blood from the radial artery for arterial blood gas analysis.