Radial artery

The radial artery is one of the two major arteries of the forearm, the other being the ulnar artery. It is a continuation of the brachial artery and is responsible for supplying oxygenated blood to the lateral aspect of the forearm, wrist, and hand. The radial artery is commonly used to measure the pulse due to its superficial location in the wrist. It is a critical vessel in the vascular system of the upper limb and plays a key role in hand circulation through its contributions to both the superficial and deep palmar arches.

Location

The radial artery begins at the bifurcation of the brachial artery in the cubital fossa, just below the elbow. From there, it runs along the lateral (thumb-side) aspect of the forearm, passing superficial to the flexor muscles. In the distal forearm, the artery becomes more superficial, making it easily palpable at the wrist, just lateral to the flexor carpi radialis tendon. The radial artery then curves around the lateral side of the wrist, passing through the anatomical snuffbox, before entering the palm of the hand, where it contributes to the formation of the deep palmar arch.

Structure and Anatomy

The radial artery is a key artery in the upper limb that supplies the forearm and hand. Its anatomy involves its origin, course, branches, and relationship to surrounding structures, making it an essential vessel for blood circulation to the lateral forearm and hand. Below is a detailed description of its anatomy.

Origin

The radial artery originates from the brachial artery, which bifurcates into the radial and ulnar arteries at the level of the cubital fossa, located just below the elbow joint. This bifurcation occurs near the neck of the radius, a bone in the forearm. The radial artery is the smaller of the two terminal branches of the brachial artery.

Course

The radial artery travels along the lateral side of the forearm and hand, following a relatively superficial path, especially in the distal portion, where it becomes easy to palpate. Its course can be divided into three main segments: the forearm, wrist, and hand.

Forearm

In the proximal part of the forearm, the radial artery lies deep to the brachioradialis muscle and is situated lateral to the flexor carpi radialis tendon. As it continues distally, it becomes more superficial, running between the tendons of the brachioradialis and flexor carpi radialis muscles.

• Proximal Course: The artery runs deep to the brachioradialis muscle, with the radial nerve located lateral to it.
• Distal Course: As the artery approaches the wrist, it lies more superficially, just under the skin and fascia, making it easily palpable.

Wrist

At the wrist, the radial artery is superficial and can be palpated on the radial side (thumb side) of the wrist. It passes lateral to the flexor carpi radialis tendon and crosses the wrist joint anteriorly. It travels just above the scaphoid bone and enters the anatomical snuffbox, a triangular depression on the lateral aspect of the wrist formed by the tendons of the extensor pollicis longus and extensor pollicis brevis muscles.

Anatomical Snuffbox: In this region, the artery lies on the dorsal side of the hand, running over the scaphoid and trapezium bones before entering the hand.

Hand

After crossing through the anatomical snuffbox, the radial artery curves into the palm of the hand. It passes between the two heads of the first dorsal interosseous muscle at the base of the thumb and enters the deep part of the hand, where it contributes to the formation of the deep palmar arch.

Deep Palmar Arch: In the palm, the radial artery forms the deep palmar arch by anastomosing (joining) with the deep branch of the ulnar artery. This arch supplies the deep structures of the palm and fingers.

Branches

The radial artery gives rise to several important branches as it travels down the forearm and hand, supplying blood to various muscles, bones, tendons, and skin. These branches include:

Radial Recurrent Artery

This branch arises shortly after the radial artery begins its course in the forearm. It runs proximally to supply the elbow joint and contributes to the anastomosis around the elbow with other arteries.

Muscular Branches

Throughout its course in the forearm, the radial artery gives off small muscular branches to supply the brachioradialis, flexor carpi radialis, and other muscles of the lateral forearm.

Palmar Carpal Branch

As the radial artery approaches the wrist, it gives off the palmar carpal branch, which contributes to the palmar carpal arch, a vascular network that supplies the carpal bones and ligaments of the wrist joint.

Dorsal Carpal Branch

This branch arises at the level of the wrist and travels dorsally (toward the back of the hand). It contributes to the formation of the dorsal carpal arch, which supplies the skin and tissues of the dorsum (back) of the hand and provides blood to the dorsal aspect of the fingers.

Superficial Palmar Branch

Before entering the anatomical snuffbox, the radial artery gives off the superficial palmar branch, which helps form the superficial palmar arch. This arch is formed primarily by the ulnar artery, but the superficial branch of the radial artery contributes to it in some individuals.

Princeps Pollicis Artery

In the hand, the radial artery gives rise to the princeps pollicis artery, which runs along the medial side of the thumb, supplying the muscles and skin of the thumb.

Radialis Indicis Artery

Another branch of the radial artery in the hand is the radialis indicis artery, which supplies the lateral side of the index finger.

Perforating Branches

The radial artery also gives off perforating branches that pass through the interosseous muscles to supply the metacarpal bones and contribute to the blood supply of the dorsal aspect of the hand.

Relationship to Surrounding Structures

The radial artery has important anatomical relationships with several key structures in the forearm and hand:

• Radial Nerve: In the proximal forearm, the radial artery runs in close proximity to the radial nerve, which lies lateral to the artery. This relationship is important for maintaining the coordinated function of the forearm and hand.
• Muscles: The radial artery passes deep to the brachioradialis muscle in the forearm but becomes superficial in the distal forearm. In the hand, it travels between the first dorsal interosseous muscle and the adductor pollicis muscle.
• Bones and Tendons: At the wrist, the radial artery passes over the scaphoid and trapezium bones and lies just lateral to the flexor tendons. Its close association with these bones and tendons makes it a critical artery for hand movements and wrist stability.

Termination

The radial artery terminates in the palm by forming the deep palmar arch, which supplies the deep structures of the hand. This arch is completed by the deep branch of the ulnar artery, forming an important vascular network that ensures an adequate blood supply to the muscles, bones, and tendons of the hand.

Variations

Anatomical variations in the radial artery are common. Some individuals may have a high-origin radial artery, where the radial artery branches off from the brachial artery higher in the arm than usual. Additionally, the contribution of the radial artery to the superficial palmar arch may vary, with some individuals having a more dominant contribution from the ulnar artery or a more robust superficial palmar branch from the radial artery.

Function

The radial artery serves several critical functions related to the vascular supply of the forearm, wrist, and hand. As one of the major arteries of the upper limb, its role in delivering oxygenated blood to these areas is vital for the normal functioning of the muscles, tendons, nerves, and bones. Below is a detailed explanation of the specific functions of the radial artery.

Blood Supply to the Lateral Forearm

The radial artery provides blood to the muscles and tissues along the lateral (thumb-side) aspect of the forearm.

• Muscular Supply: The radial artery delivers oxygenated blood to several important muscles in the forearm, including the brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis. These muscles are involved in movements such as wrist extension and radial deviation (moving the hand toward the thumb side).
• Tissue Nourishment: The artery supplies the skin, fascia, and connective tissues along the lateral side of the forearm, ensuring the health and proper function of these tissues.

Blood Supply to the Elbow Joint

The radial artery plays a key role in supplying blood to the elbow joint through its radial recurrent artery, which forms part of the anastomotic network around the elbow.

Elbow Flexion and Extension Support: The radial recurrent artery supplies blood to the muscles and joint capsule of the elbow, ensuring smooth and stable movements during flexion and extension of the forearm.

Blood Supply to the Wrist

The radial artery provides blood to the bones, ligaments, and tendons of the wrist through its branches, ensuring the proper function and mobility of the wrist joint.

• Palmar and Dorsal Carpal Branches: These branches of the radial artery form the palmar carpal arch and dorsal carpal arch, supplying blood to the carpal bones and associated ligaments. This helps maintain the stability of the wrist joint, supporting both flexion and extension.
• Anatomical Snuffbox: As the radial artery passes through the anatomical snuffbox, it supplies the scaphoid and trapezium bones, which are key components of the wrist joint. This blood flow is essential for maintaining bone health and preventing avascular necrosis, particularly in the scaphoid bone.

Formation of the Deep Palmar Arch

The radial artery plays a critical role in forming the deep palmar arch, which supplies the deep structures of the hand, including the muscles, bones, and tendons. This is one of the artery’s most important functions in the hand.

Deep Palmar Arch: The radial artery forms the deep palmar arch by anastomosing (joining) with the deep branch of the ulnar artery. This arch supplies the deep muscles of the hand, such as the interosseous muscles and adductor pollicis, which are crucial for fine motor control and gripping.

Contribution to the Superficial Palmar Arch

In addition to forming the deep palmar arch, the radial artery also contributes to the superficial palmar arch in some individuals. The superficial palmar arch primarily supplies the skin and more superficial structures of the hand, particularly the palmar surface.

Superficial Palmar Branch: The radial artery gives off a superficial palmar branch, which contributes to the formation of the superficial palmar arch. This arch ensures that the muscles, tendons, and skin of the palm receive adequate blood supply.

Blood Supply to the Thumb and Index Finger

The radial artery is the main source of blood to the thumb and the lateral aspect of the index finger, ensuring that these digits remain functional and healthy.

• Princeps Pollicis Artery: The princeps pollicis artery, a branch of the radial artery, supplies blood to the thumb. This artery runs along the medial side of the thumb and provides blood to its muscles, skin, and tendons, ensuring that the thumb is well-nourished for movements like flexion, extension, and opposition (touching the thumb to the other fingers).
• Radialis Indicis Artery: The radialis indicis artery, another branch of the radial artery, supplies the lateral side of the index finger. This artery is crucial for ensuring that the index finger has a consistent blood supply for precision tasks such as writing, gripping, and typing.

Collateral Circulation and Anastomosis

The radial artery is a key player in the collateral circulation of the forearm and hand, ensuring that blood flow can be maintained even if one of the main arteries is blocked or compromised.

• Anastomoses with Ulnar Artery: The radial artery forms anastomoses with the ulnar artery through both the superficial and deep palmar arches. This connection allows blood flow to continue between these two arteries, providing a backup route in case one artery is compromised.
• Support During Vascular Compromise: In cases of arterial occlusion or injury to the ulnar artery, the radial artery can take over and provide sufficient blood flow to the hand and fingers, preventing ischemia (lack of blood supply) and ensuring continued function of the hand.

Oxygen and Nutrient Delivery

Like all arteries, the radial artery’s fundamental role is to deliver oxygen and nutrients to the tissues it supplies. This is crucial for the health and maintenance of muscles, tendons, skin, and bones throughout the forearm and hand.

• Tissue Repair and Maintenance: The radial artery ensures that the tissues it supplies receive the oxygen and nutrients needed for repair and maintenance, especially after injury or strain. This is important for maintaining the health and function of the forearm and hand’s structures.
• Skin and Subcutaneous Tissue Nourishment: The radial artery also delivers blood to the skin and subcutaneous tissues of the lateral forearm and hand, ensuring that the skin remains healthy, flexible, and capable of healing from cuts and abrasions.

Contribution to Hand Function and Dexterity

The radial artery’s role in supplying blood to the thumb, index finger, and muscles of the hand is essential for fine motor control and dexterity.

• Grip Strength and Coordination: By ensuring that the muscles responsible for thumb and finger movements receive an adequate blood supply, the radial artery supports both gross and fine motor skills. It allows for strong grips as well as precise movements such as pinching or writing.
• Thumb and Finger Movements: The blood supply to the thumb and index finger, provided by the radial artery’s branches (princeps pollicis and radialis indicis arteries), is critical for movements like opposition (thumb touching other fingers) and flexion, which are essential for a wide range of manual tasks.

Clinical Significance

The radial artery is of great clinical importance due to its superficial location and vital role in supplying blood to the forearm, wrist, and hand.

• Pulse Measurement: The radial artery is commonly used to check the pulse because of its superficial location at the wrist, where it can be easily palpated. This makes it a key artery for assessing heart rate and circulation in clinical settings.
• Access for Medical Procedures: The radial artery is frequently used in medical procedures such as arterial line insertion for continuous blood pressure monitoring or blood sampling, and in coronary angiography or coronary artery bypass grafting (CABG), where it may be used as a graft.
• Vascular Compromise: Conditions such as radial artery occlusion (due to thrombosis or trauma) can compromise blood supply to the hand, particularly the thumb and index finger, leading to ischemia. However, the radial artery’s anastomoses with the ulnar artery provide a collateral blood supply, minimizing the risk of tissue damage in most cases.