Superficial branch of radial nerve

The superficial branch of radial nerve originates at the level of the lateral epicondyle of the humerus, at the upper border of the supinator muscle, where the radial nerve bifurcates into its superficial (sensory) and deep (motor) branches.

Course

While the deep branch passes between the two heads of the supinator and winds around the lateral side of the radius, the superficial branch, a purely sensory continuation of the radial nerve, descends in the anterior forearm. It courses beneath the brachioradialis muscle, traveling alongside the radial artery in the middle third of the forearm.

In the distal forearm, the nerve turns laterally, passing deep to the tendon of the brachioradialis. It then pierces the deep fascia and emerges on the dorsum of the hand.

Innervation

Upon reaching the dorsum of the hand, the superficial branch of radial nerve divides near the radial styloid process into four or five dorsal digital branches:

• First branch: Innervates the skin over the radial side of the thumb and adjoining thenar eminence. It communicates with branches of the lateral antebrachial cutaneous nerve.

• Second branch: Supplies the skin on the medial side of the thumb.

• Third branch: Supplies the skin on the lateral side of the index finger.

• Fourth branch: Innervates the second interdigital space, supplying the adjoining sides of the index and middle fingers.

• Fifth branch: Innervates the third interdigital space, supplying the adjoining sides of the middle and ring fingers. It also forms connections with the dorsal branch of the ulnar nerve.

Note

The distal dorsal aspects of the fingers (nail beds) are supplied by the median nerve.