The radial artery is one of the two terminal branches of the brachial artery (a major blood vessel of the upper arm), which divides at the cubital fossa. It is one of the main arteries supplying blood to the forearm structure. The radial artery is smaller in size than the ulnar, the other bifurcation of the brachial artery.
Anatomical Origin
As the brachial artery (a continuation of the axillary artery) continues down the arm and reaches just below the bend of the elbow. It is bifurcated into the radial and ulnar arteries. The ulnar passes down on the medial side of the forearm. While the radial continues downward on the distal side of the forearm to the wrist.
Forearms
In the forearm, the radial artery assumes along the radial side of the forearm. Deep to the brachioradialis muscle and lateral to the digitorum superficialis as well as flexor pollicis longus tendons.
For the distal aspect of its course, it arises from underneath brachioradialis. It continues down the path while being enclosed by the border of the radius, and the flexor carpi radialis tendon.
During this course, the radial artery superficially situated close to the surface on the underside of the forearm, only protected by the fascia and skin.
Wrist and Hand
At the wrist, the radial artery traverses across the floor of the anatomical snuffbox and spirals around the lateral side of the wrist. It runs under the tendons of Abductor pollicis longus, extensor pollicis long, and Brevis. Which is situated between the metacarpus structure of the index finger and thumb.
It then passes between the upper ends of the first Interosseous dorsalis and goes deep into the palm.
In the metacarpal region, the radial artery gives rise to the deep volar arch and unites with the adjacent branches of the ulnar artery to supply blood in the hand. As a result, the radial artery forms two arterial arches:
Deep volar arch
which lies proximal to the palmar aponeurosis and superficial to the flexor tendons of the hand. It transports oxygenated blood to the wrist joint and the carpal bones.
Superficial palmar arch
which lies anterior to the flexor tendons and deep to the palmar aponeurosis in the hand. It forms the digital arteries that supply blood to the four fingers of the hand.
Functions
As the main artery of the posterolateral aspect of the forearm, the radial artery is responsible for delivering blood to lateral forearm muscles, as well as the vascular territories. This includes the elbow joint, the carpal tunnel bones, radial nerves, the thumb, and the lateral index finger.
Due to its size and superficial location, close to the surface of the underside of the forearm. The pulse of the radial artery is easily palpated at the wrist. The primary reason why the radial artery used routinely to measure a patient’s heart rate.
In addition, the radial artery commonly used to draw blood for the arterial blood gas (ABG) tests. Which determines the oxygen and carbon dioxide levels in a patient’s blood.
The radial artery is ideal for this test since it is accessible, it poses no danger to the patient, and due to its close proximity to the ulnar – which will take over for blood draw if the radial is damaged.
Most often ABG tests are carried out as part of intensive care practices.
Branches of radial artery
Undoubtedly, the radial artery visualized in three segments, one in the forearm (beginning with the brachial artery), the second at the face of the wrist, and the final in the hand. Across its path from the forearm through the wrist and down to the hand, the radial artery splits into several branches.
These may be divided into three groups, based on the regions in which the vessels are located.
- In the Forearm:
- Radial recurrent artery
- Muscular branches
- Besides, the Palmar carpal branch
- Superficial volar
- At the Wrist:
- Dorsal carpal branch
- First dorsal metacarpal
- In the Hand:
- Princeps pollicis artery
- Volar metacarpal arteries
- Also, Radialis indicis artery
- Perforating recurrent artery
Muscular Branches
The smaller muscular branches are distributed to the muscles on the radial aspect of the forearm. which prominently includes the posterior compartment and extensor muscles. However, the muscular branches are not the only blood supply source for the posterior compartment.
Certain regions of the forearm extensors are connected with the anterior and posterior interosseous arteries. The latter of which is a branch of the ulnar artery.
Radial Recurrent Artery
The radial recurrent artery is the largest lateral branch of the radial artery. It arises at the lower end of the elbow, distal to the bifurcation point of the brachial artery.
The vessel follows proximally to the supinator muscle, before continuing on its path between the Brachioradialis and Brachialis. It finally anastomoses with the terminal part of the radial collateral artery.
The radial recurrent artery is an important blood vessel for the elbow joint and muscles of the region.
Palmar Carpal Branch
To clarify, this small branch of this artery originates near the distal boundary of the pronator quadratus muscle and continues across the anterior surface of the carpus region.
It reconnects with the palmar carpal branch of the ulnar artery and the interosseous arteries in the anterior compartment of the forearm, thus forming the palmar carpal arch.
Superficial Volar Branch
The superficial volar branch splits from the radial artery just as it winds around the lateral aspect of the wrist. As it moves through, and at times across, the muscles at the base of the thumb, the superficial volar branch anastomoses with the terminal segment of the ulnar artery to complete the superficial palmer arch.
Throughout its course, the vessel varies in size – at times small enough to end in the tendons of the thumb, and on the other hand large enough to appear as a continuation of the radial artery.
Dorsal Carpal Branch
At the proximal point of the anatomical snuffbox, it divides into the small dorsal carpal branch and continues down the middle of the wrist. Later, the dorsal carpal conjoin with the ulnar and posterior interosseous arteries to shape the dorsal carpal arch.
Deep Palmer Branch
The deep palmer branch arises from the terminal part of the radial artery to form the deep palmer arch, in combination with the deep palmer branch of the ulnar. It passes through the palm, as well as between the end sections of metacarpal bones and flexor tendons in the fingers.
First Dorsal Metacarpal Artery
This vessel splits from the radial artery just before it courses between the two upper ends of the first Interosseous dorsalis. It immediately branches off to the adjacent sides of the thumb and the index finger. A direct branch from the radial artery also supplies to the radial aspect of the thumb.
Princeps Policies and Radial’s Indices Artery
Just as the radial artery reaches the webspace connecting the thumb and index finger, it diverges into two branches, namely the princeps pollicis and radialis indicis arteries. Indeed, these are located on the dorsal side of the hand.
The Princeps pollicis serves as the main blood supply to the thumb and branches off into two vessels down its course. Also, the radial indices are situated over the distal aspect of the index and supply blood to the lateral segment of the finger.
Clinical Significance
Although the radial artery isn’t the sole provider of blood supply to the hand and forearm, any side effects from diseases or disorders can severely impact major bodily functions. Several problematic conditions can stem from compromised blood circulation to the region encompassed by the radial artery.
Carpal Tunnel Syndrome
While it may not be the leading cause of carpal tunnel syndrome, in around 3% of the cases the issue stems from complications of the radial artery. Symptoms may include numbing, pain or tingling feeling the arm or hand.
Raynaud’s Syndrome
Problems with the radial artery can also cause Raynaud’s Syndrome. It is a common condition that affects around 20% of the world’s population. Raynaud’s disease causes the arteries and veins in the hand, including the branches of the radial artery to shrink in response to colder temperatures.
This in turn causes numbing in the region affects the mobility of the hand. As the blood supply to the region is restricted, the skin of the hands also turns pale and blue.
Upper Extremity Arterial Occlusive Disease
One of the leading causes of upper extremity arterial occlusive disease is atherosclerosis, commonly referred to as the thickening and stiffening of the arteries. On the whole, it causes disruption of proper blood circulation to the upper limbs.
While commonly occurring in the lower limbs, upper segments of the body can also be affected by this disease. The Symptoms can be as mild as cramps and slight tightness, to visible pain and weakness of the arm muscles.
If you’re experiencing any discomfort in the region or unusual symptoms for some time, it’s always best to consult your physician. They may be able to give a proper diagnosis following examination, questioning, tests, and thorough evaluation of your medical history.
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ICD (International Classification of Diseases)