Nerve
Radial nerve
Major supply to the posterior arm and forearm
High-yield
The nerve lies close to the humeral shaft in the radial groove. Damage there can cause wrist drop, but the exact muscle and skin deficits depend on which branches leave above the injury.
Overview
A continuation of the posterior cord, the radial nerve reaches the back of the arm and then returns toward the front of the elbow. Its branches power many extensors and carry sensation from parts of the posterior limb and hand.
Learning this group? Read How to learn the brachial plexus.
Reference facts
- Root value
- Posterior cord fibers from C5-T1
- Course
- Through the triangular interval and radial groove with the deep brachial artery; across the lateral intermuscular septum toward the elbow; divides into superficial and deep branches, with the latter continuing through supinator as the posterior interosseous nerve
- Motor
- Triceps, anconeus, brachioradialis, supinator and the posterior forearm muscles that extend the wrist, fingers and thumb
- Sensory
- Parts of the posterior/inferolateral arm and posterior forearm; dorsolateral hand and proximal dorsal thumb-side digits. Fingertips and nail beds are mainly median or ulnar territories
Mnemonic
Remember the posterior muscle group, then add two useful exceptions to the extension theme: brachioradialis bends the elbow, and supinator rotates the forearm.
Clinical correlation
Humeral injury or prolonged pressure on the arm can impair radial nerve function. A lesion of only the superficial branch causes sensory symptoms without wrist-extensor paralysis; a proximal lesion can affect both movement and sensation.
Frequently asked questions
What are the roots of the radial nerve?
Posterior cord fibers from C5-T1.
What muscles does the radial nerve supply?
The radial nerve supplies the triceps, anconeus, brachioradialis, supinator and the posterior forearm muscles that extend the wrist, fingers and thumb.
What is the sensory distribution of the radial nerve?
Parts of the posterior/inferolateral arm and posterior forearm; dorsolateral hand and proximal dorsal thumb-side digits. Fingertips and nail beds are mainly median or ulnar territories.
What is the course of the radial nerve?
Through the triangular interval and radial groove with the deep brachial artery; across the lateral intermuscular septum toward the elbow; divides into superficial and deep branches, with the latter continuing through supinator as the posterior interosseous nerve.