Radial Nerve

Radial nerve originates from the posterior cord of the brachial plexus. It leaves the axilla to enter the posterior compartment of the arm. It enters the anterior compartment just above the lateral epicondyle. It winds around the back of arm in the spiral groove between the heads of the triceps muscle. Radial nerve pierces the lateral fascial septum above the elbow and continues downwards into the cubital fossa in front of the elbow, between the brachialis and brachioradialis muscle.

Grey’s Anatomy 20th edition

1. In the axilla, radial nerve supplies the long and medial head of the triceps and gives off the posterior cutaneous nerve of the arm.

2. In the spiral groove, radial nerve is accompanied by the profunda vessels and lies directly in contact with the shaft of humerus. It supplies the lateral and medial heads of the triceps, anconeus and gives off lower lateral cutaneous nerve of the arm (which supplies the lateral and anterior side of the arm) as well as the posterior cutaneous nerve of the forearm (which supplies till the wrist joint).

Cutaneous Nerve Supply of Arm, Forearm and Hand

Grey’s Anatomy 20th edition

3. In the anterior compartment, radial nerve supplies the brachialis, brachioradialis, extensor carpi radialis longus and gives off articular branches to the elbow joint.

The radial nerve passes down in front of the lateral epicondyle between the brachialis on its medial side and the brachioradialis and the the extensor carpi radialis longus on the lateral side.

At the level of the lateral epicondyle, radial nerve divides into superficial and deep branches.

Muscular branches:

Muscular branches supply the brachioradialis, extensor carpi radialis longus and the lateral part of brachialis muscle.

Articular branches:

Articular branches supply the elbow joint.

a. Superficial branch:

Superficial branch is the direct continuation of the radial nerve, after the deep branch is given off in front of the lateral epicondyle. It runs down under cover of the brachioradialis muscle on the lateral side of the radial artery. In the distal part of the forearm, the radial nerve leaves the radial artery and passes backwards under the tendon of the brachioradialis. It reaches the posterior surface of the wrist and divides into terminal branches which supply the skin on the lateral two-third of the posterior surface of hand and the posterior surface over proximal phalanges, as well as the lateral three and a half fingers. The area supplied over the dorsum is subject to variation.

Grey’s Anatomy 20th edition

b. Deep Branch:

The deep branch of the radial nerve winds around the neck of radius within the supinator muscle and pierces it to reach the posterior compartment of the forearm. It descends in the interval between the the superficial and deep groups to reach the posterior surface of the wrist joint.

Muscular branches:

Muscular branches supply the extensor carpi radialis brevis, supinator, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis and indicis.

Articular branches:

Articular branches supply the wrist and the carpal joints.

Superficial Palmar Arch

Grey’s Anatomy 20th edition

Deep Palmar Arch

Grey’s Anatomy 20th edition