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.
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.