Radial Artery

Introduction

Introduction to the Radial Artery in the Forearm

The radial artery is the smaller of the two terminal branches of the brachial artery and is the principal lateral arterial channel of the forearm. It supplies the lateral aspect of the forearm muscles, the wrist, and the hand, and is clinically indispensable for arterial blood gas sampling, percutaneous coronary intervention, and monitoring of the peripheral pulse. Its course through the forearm, wrist, and hand is precisely defined by fascial planes and bony landmarks, making it predictable for surgical and interventional procedures.

This module provides a detailed account of the origin, course, relations, branches, anatomical variations, and clinical relevance of the radial artery in the forearm.

Study

1. Origin and Termination

The radial artery arises from the bifurcation of the brachial artery in the cubital fossa, approximately 1 cm distal to the elbow crease, opposite the neck of the radius. It is the direct continuation of the brachial artery, while the ulnar artery deviates medially. The radial artery terminates in the hand by forming the deep palmar arch, after anastomosing with the deep branch of the ulnar artery.

2. Course and Relations in the Forearm

From its origin, the radial artery descends vertically along the lateral aspect of the forearm. In the proximal third, it lies deep to the brachioradialis muscle and is related medially to the pronator teres tendon. It then runs distally, lying successively on the tendons of the biceps brachii insertion, the supinator, the pronator teres, the radial head of the flexor digitorum superficialis (FDS), the flexor pollicis longus, and finally the pronator quadratus.

Throughout its course, the radial artery is accompanied by a pair of venae comitantes. The superficial branch of the radial nerve lies lateral to the artery in the middle third, but the artery and nerve are separated by the brachioradialis tendon in the distal third.

Distally, the radial artery leaves the anterior compartment by winding around the lateral aspect of the wrist, deep to the tendons of abductor pollicis longus and extensor pollicis brevis (first extensor compartment), crossing the floor of the anatomical snuffbox. It then pierces the first dorsal interosseous muscle to enter the palm.

3. Branches in the Forearm

The radial artery gives several named branches within the forearm:

Radial recurrent artery: Arises just distal to the origin, ascends between the brachioradialis and brachialis muscles, and anastomoses with the radial collateral branch of the profunda brachii artery, contributing to the peri‑articular anastomosis of the elbow.

Muscular branches: Numerous small vessels supply the lateral forearm muscles, particularly the brachioradialis, extensor carpi radialis longus and brevis, supinator, and flexor pollicis longus.

Palmar carpal branch: A small vessel that arises near the distal border of the pronator quadratus and runs medially to anastomose with the palmar carpal branch of the ulnar artery and the anterior interosseous artery, forming the palmar carpal arch.

Superficial palmar branch: Arises just before the radial artery curves dorsally. It passes through or superficial to the thenar muscles and joins the terminal part of the ulnar artery to complete the superficial palmar arch. This branch is variable in size and can be dominant.

Dorsal carpal branch: Arises at the wrist level, runs medially deep to the extensor tendons, and anastomoses with the dorsal carpal branch of the ulnar artery and the anterior and posterior interosseous arteries to form the dorsal carpal arch.

4. Anatomical Variations

The radial artery may originate from the axillary artery or from a high bifurcation of the brachial artery (above the cubital fossa). Its course can be superficial, running over the brachioradialis instead of under it (superficial dorsal radial artery). These variations influence the palpability of the pulse and the feasibility of cannulation.

5. Clinical Relevance

Radial artery pulse: Palpable against the distal radius between the tendons of brachioradialis and flexor carpi radialis. Used for routine cardiovascular assessment and to evaluate peripheral vascular disease.

Arterial cannulation: The radial artery is the most common site for arterial line placement and coronary angiography. Allen’s test is performed before cannulation to ensure adequate collateral circulation via the ulnar artery.

Radial artery laceration: A deep laceration at the wrist may sever the radial artery, leading to pulsatile bleeding. Ligation is possible if ulnar circulation is intact.

Thrombosis and spasm: Repeated cannulation or trauma can cause thrombosis or severe spasm, compromising distal hand perfusion.

Summary

Summary of the Radial Artery in the Forearm

The radial artery is the lateral terminal branch of the brachial artery, coursing deep to brachioradialis and on the forearm flexor muscles. It provides muscular, recurrent, and carpal branches, ultimately entering the hand to form the deep palmar arch. Its superficial position at the wrist makes it ideal for pulse assessment and invasive procedures, provided collateral circulation is intact.