Radial nerve
Nervus radialis
NervousNervesArmLeft and right
View left in 3D View right in 3D
- What it is
- The largest branch of the posterior cord. It winds around the back of the humerus in the spiral groove between the heads of triceps, pierces the lateral intermuscular septum to reach the front of the lateral elbow, and there splits into a superficial sensory branch running down the lateral forearm to the back of the hand, and a deep branch that turns through supinator into the back of the forearm as the posterior interosseous nerve.
- Function
- Motor to triceps, brachioradialis, supinator and every extensor of the wrist, fingers and thumb; sensation from the back of the arm and forearm and the thumb side of the back of the hand.
- Size
- About 4 mm thick; ~55 cm long
- Clinical note
- A mid-shaft humeral fracture, or sleeping with the arm hung over a chair ("Saturday night palsy"), damages it in the spiral groove and causes wrist drop; the triceps is usually spared because its branches arise higher.