Nerve
Radial nerve
The great extensor nerve
High-yield
Runs in the radial (spiral) groove of the humerus; midshaft fracture → wrist drop and loss of extension. 'BEST' muscles.
Overview
The largest branch of the brachial plexus and continuation of the posterior cord, supplying all extensors of the arm and forearm.
Learning this group? Read How to learn the brachial plexus.
Reference facts
- Roots
- C5, C6, C7, C8, T1 (posterior cord)
- Course
- Passes through the triangular interval into the radial groove of the humerus, then anterior to the lateral epicondyle where it divides into deep (posterior interosseous) and superficial branches
- Motor
- Triceps brachii, anconeus, brachioradialis, supinator, and all posterior forearm extensors
- Sensory
- Posterior arm and forearm; dorsolateral hand and dorsum of the lateral 3½ digits (proximal to the nail beds)
Mnemonic
Radial supplies BEST muscles: Brachioradialis, Extensors, Supinator, Triceps.
Clinical correlation
Midshaft humeral fracture → wrist drop; 'Saturday night palsy' from prolonged arm compression.
Frequently asked questions
What are the roots of the radial nerve?
The radial nerve arises from C5, C6, C7, C8, T1 (posterior cord).
What muscles does the radial nerve supply?
The radial nerve supplies the triceps brachii, anconeus, brachioradialis, supinator, and all posterior forearm extensors.
What is the sensory distribution of the radial nerve?
The radial nerve carries sensation from the posterior arm and forearm; dorsolateral hand and dorsum of the lateral 3½ digits (proximal to the nail beds).
What is the course of the radial nerve?
Passes through the triangular interval into the radial groove of the humerus, then anterior to the lateral epicondyle where it divides into deep (posterior interosseous) and superficial branches.