What is the origin and course of the radial nerve?

The radial nerve originates from the posterior cord of the brachial plexus (C5–T1). It courses through the spiral groove of the humerus, pierces the lateral intermuscular septum, and divides into deep and superficial branches in the cubital fossa.

What muscles does the radial nerve innervate?

The radial nerve innervates muscles including the triceps, anconeus, brachialis (lateral part), brachioradialis, ECRL, ECRB, supinator, and all posterior forearm extensors.

What sensory areas does the radial nerve supply?

The radial nerve supplies sensory areas including the posterior arm and forearm, lateral dorsum of the hand, and dorsal surfaces of the lateral 3½ digits (except nail beds).

What are the symptoms of a radial nerve injury in the axilla?

An axillary radial nerve injury results in motor loss (wrist drop from weak elbow, wrist, and finger extension) and sensory loss in the posterior arm, forearm, lateral hand, and dorsal 3½ digits. Supination is lost in extended elbow but preserved in flexion.

How does a spiral groove injury differ from an axillary injury to the radial nerve?

A spiral groove injury spares the triceps but causes wrist drop from loss of wrist and finger extension, with sensory loss on the dorsum of the hand, especially between the 1st and 2nd metacarpals.

What is radial tunnel syndrome and its symptoms?

Radial tunnel syndrome is an elbow entrapment causing pain over the extensor forearm and motor loss in finger and wrist extension, without wrist drop.

Radial Nerve Anatomy – Course, Branches & Wrist Drop